Publications

characterization of the water oxidizing complex of photosystem ii of the chl d-containing cyanobacterium acaryochloris marina via its reactivity towards endogenous electron donors and acceptors.	acaroychloris (a.) marina is a unique oxygen evolving organism that contains a large amount of chlorophyll d (chl d) and only very few chl a molecules. this feature raises questions on the nature of the photoactive pigment, which supports light-induced oxidative water splitting in photosystem ii (ps ii). in this study, flash-induced oxygen evolution patterns (fiops) were measured to address the question whether the s(i) state transition probabilities and/or the redox-potentials of the water oxid ...	2006	16855726
differentiating sex chromosomes of the dioecious spinacia oleracea l. (spinach) by fish of 45s rdna.	spinacia oleracea l. (spinach) is a dioecious species with both male and female plants having 2n = 2x = 12 chromosomes, consisting of two large metacentrics, two long subtelocentrics, two short subtelocentrics, two acrocentrics, and four submetacentrics. the location of 45s rdna was investigated on metaphase chromosomes using fluorescence in situ hybridization (fish). the numbers of 45s rdna foci in diploid sets of chromosomes from females was six and from males was five. all the fluorescent foc ...	2006	16825771
the rate of intestinal absorption of natural food folates is not related to the extent of folate conjugation.	evidence is conflicting as to whether the bioavailability of food folates is influenced by the extent of their conjugation.	2006	16825692
lipids in oxygen-evolving photosystem ii complexes of cyanobacteria and higher plants.	lipids in dimeric photosystem ii complexes prepared from two species of cyanobacteria, thermosynechococcus vulcanus and synechocystis sp. pcc6803, and two higher plants, spinach and rice, were analyzed to determine how many lipid molecules and what class of lipids are present in the photosystem ii complexes. it was estimated that 27, 20, 8, and 7 lipid molecules per monomer are bound to the dimeric photosystem ii complexes of t. vulcanus, synechocystis, spinach, and rice, respectively. in each o ...	2006	16822813
an inserted loop region of stromal ascorbate peroxidase is involved in its hydrogen peroxide-mediated inactivation.	ascorbate peroxidase isoforms localized in the stroma and thylakoid of higher plant chloroplasts are rapidly inactivated by hydrogen peroxide if the second substrate, ascorbate, is depleted. however, cytosolic and microbody-localized isoforms from higher plants as well as ascorbate peroxidase b, an ascorbate peroxidase of a red alga galdieria partita, are relatively tolerant. we constructed various chimeric ascorbate peroxidases in which regions of ascorbate peroxidase b, from sites internal to ...	2006	16817898
pythiogeton zizaniae, a new species causing basal stalk rot of water bamboo in taiwan.	a new species, pythiogeton zizaniae, was isolated from diseased water bamboo (zizania latifolia) in central taiwan. the organism formed a colony with scanty mycelia and mycelial aggregates on rye-water bamboo medium. special treatments were required for production of sporangia which were terminal, noncaducous and mostly ovoid. chlamydospores were absent. the fungus was homothallic. oogonia produced on v-8 water bamboo medium in water were mostly globose to subglobose and each was attached with a ...	2006	16800309
accumulation of glycinebetaine in rice plants that overexpress choline monooxygenase from spinach and evaluation of their tolerance to abiotic stress.	glycinebetaine (gb), a quaternary ammonium compound, is a very effective compatible solute. in higher plants, gb is synthesized from choline (cho) via betaine aldehyde (ba). the first and second steps in the biosynthesis of gb are catalysed by choline monooxygenase (cmo) and by betaine aldehyde dehydrogenase (badh), respectively. rice (oryza sativa), which has two genes for badh, does not accumulate gb because it lacks a functional gene for cmo. rice plants accumulate gb in the presence of exoge ...	2006	16790464
quinaldine derivatives: preparation and biological activity.	the series of quinaldine derivatives were prepared, some of them by means of novel synthetic methods. the synthetic approach, analytical and spectroscopic data of all newly synthesized compounds are presented. the prepared compounds were tested for their in vitro antifungal activity as well as for their photosynthesis-inhibiting activity (the inhibition of photosynthetic electron transport in spinach chloroplasts (spinacia oleracea l.) and the reduction of chlorophyll content in chlorella vulgar ...	2005	16787342
quality control of photosystem ii. cleavage of reaction center d1 protein in spinach thylakoids by ftsh protease under moderate heat stress.	when spinach thylakoids were subjected to moderate heat stress (40 degrees c for 30 min), oxygen evolution was inhibited, and cleavage of the reaction center-binding protein d1 of photosystem ii took place, producing 23-kda n-terminal fragments. the d1 cleavage was greatly facilitated by the addition of 0.15 mm zncl2 and 1 mm atp and was completely inhibited by 1 mm edta, indicating the participation of an atp-dependent metalloprotease(s) in the d1 cleavage. herbicides 3-(3,4-dichlorophenyl)-1,1 ...	2006	16735503
refinement of the structural model for the photosystem ii supercomplex of higher plants.	recent x-ray structures determined for the photosystem ii (psii) core complex isolated from cyanobacteria have provided important information for understanding the functionality of this photosynthetic enzyme including its water splitting activity. as yet, no high-resolution structure is available for psii of plants or eukaryotes in general. however, crystal structures have been determined for some components of plant psii which together with the cyanobacterial structure can be used to interpret ...	2006	16729961
identification of critical arginine residues in the functioning of rubisco activase.	rubisco activase is a member of the aaa(+) family in which arginines located in the box vii and sensor 2 domains are a recurrent feature and typically contribute to atp-binding/hydrolysis or an inter-subunit interface. replacement of r241 or r244 in box vii or r294 or r296 in sensor 2 with alanine in tobacco activase did not greatly alter the binding of atp or adp. however, atp hydrolysis was minimal (r241a and r244a) or greatly diminished (r296a) and none of these mutants were able to activate ...	2006	16712773
description of a novel panallergen of cross-reactivity between moulds and foods.	the present investigation is undertaken to demonstrate a novel cross-reactivity between aeroallergens (moulds fungi imperfecti) and allergens from foods (spinach and mushroom agaricus bisporus). we have performed a dual study in vivo and in vitro, in a population of atopic patients. data from in vivo tests performed with spinach and mushroom have been statistically analysed. to the in vitro assays, mushroom and spinach extracts have been obtained, and sera from moulds allergic patients analysed ...	2006	16698676
circadian rhythms of the l-ascorbic acid level in euglena and spinach.	plant defenses against photo-oxidative stress have been studied almost exclusively with respect to stress responses, and little is known about how non-enzymic antioxidants change under constant conditions without a time cue or an environmental stress. here, we show that, in both the flagellated alga euglena gracilis z and the angiosperm spinacia oleracea l., the potent antioxidant l-ascorbic acid (asc) displays a circadian rhythm with a maximum at subjective midday, a physiological state reflect ...	2006	16679025
structure and dynamics of the n-terminal loop of psbq from photosystem ii of spinacia oleracea.	infrared and raman spectroscopy were applied to identify restraints for the structure determination of the 20 amino acid loop between two beta-sheets of the n-terminal region of the psbq protein of the oxygen evolving complex of photosystem ii from spinacia oleracea by restraint-based homology modeling. one of the initial models has shown a stable fold of the loop in a 20 ns molecular dynamics simulation that is in accordance with spectroscopic data. cleavage of the first 12 amino acids leads to ...	2006	16678136
phosphorylation of the spinach chloroplast 24 kda rna-binding protein (24rnp) increases its binding to petd and psba 3' untranslated regions.	the chloroplast 24 kda rna binding protein (24rnp) from spinacea oleracea is a nuclear encoded protein that binds the 3' untranslated region (3'utr) of some chloroplast mrnas and seems to be involved in some processes of mrna metabolism, such as 3'utr processing, maturation and stabilization. the 24rnp is similar to the 28rnp which is involved in the correct maturation of petd and psba 3'utrs, and when phosphorylated, decreases its binding affinity for rna. in the present work, we determined tha ...	2006	16675088
lithium decreases cold-induced microtubule depolymerization in mesophyll cells of spinach.	freezing, dehydration, and supercooling cause microtubules in mesophyll cells of spinach (spinacia oleracea l. cv bloomsdale) to depolymerize (me bartolo, jv carter [1991] plant physiol 97: 175-181). the objective of this study was to gain insight into the question of whether microtubules depolymerize as a direct response to environmental stresses or as an indirect response to cellular changes that accompany the stresses. leaf sections of spinach were treated with li(+) before and during exposur ...	1992	16669100
identification and levels of 2'-carboxyarabinitol in leaves.	2'-carboxyarabinitol 1-phosphate (ca1p) is a naturally occurring inhibitor of ribulose-1,5 bisphosphate carboxylase/oxygenase activity. a chloroplast phosphatase has previously been identified that degrades ca1p in vitro to carboxyarabinitol (ca) plus phosphate, but ca has not yet been detected in plants. here, we detail procedures to isolate and assay ca from leaves and utilize mass spectrometry to demonstrate for the first time that ca is present in plants. ca was present in leaves of all 13 s ...	1992	16669072
regulation of photosynthesis by end-product accumulation in leaves of plants storing starch, sucrose, and hexose sugars.	in the present study, leaves of different plant species were girdled by the hot wax collar method to prevent export of assimilates. photosynthetic activity of girdled and control leaves was evaluated 3 to 7 days later by two methods: (a) carbon exchange rate (cer) of attached leaves was determined under ambient co(2) concentrations using a closed gas system, and (b) maximum photosynthetic capacity (a(max)) was determined under 3% co(2) with a leaf disc o(2) electrode. starch, hexoses, and sucros ...	1992	16669056
identification of factors regulating the phosphorylation status of sucrose-phosphate synthase in vivo.	the purpose of this study was to identify the factors that control sucrose-phosphate synthase (sps)-kinase and sps-protein phosphatase (sps-pp) activity in situ, and thereby mediate the activation of sps by light or mannose. feeding mannose to excised spinach (spinacia oleracea) leaves in darkness resulted in a general sequestration of cellular phosphate (as evidenced by accumulation of mannose-6-p and depletion of glucose-6-p [glc-6-p] and fructose-6-p [fru-6-p]) and a relatively slow activatio ...	1992	16669055
regulation of plastid gene expression during photooxidative stress.	we have used the carotenoid biosynthesis inhibitor norflurazon to study the relationship between chloroplast and nuclear gene expression and the mechanisms by which plastid mrna accumulation is regulated in response to photooxidative stress. by treating 4-week-old hydroponic spinach plants (spinacea oleracea), we were able to determine the response at two distinct stages of chloroplast development. for all parameters studied, differences were found between the norflurazon-treated young and matur ...	1992	16669052
association of 70-kilodalton heat-shock cognate proteins with acclimation to cold.	exposure of young spinach seedlings (spinacia oleracea l. cv bloomsdale) to 5 degrees c leads to an increase in the synthesis of several 79-kilodalton proteins that are present in leaf tissue grown at 20 degrees c. protein sequence analyses and immunological cross-reactivity indicate that this group of proteins belongs to the 70-kilodalton heat-shock family. steady-state transcript levels and protein synthesis are increased two- to threefold within 1 day, but immunoblot analyses suggest that the ...	1992	16669045
dissociation of ribulose-1,5-bisphosphate bound to ribulose-1,5-bisphosphate carboxylase/oxygenase and its enhancement by ribulose-1,5-bisphosphate carboxylase/oxygenase activase-mediated hydrolysis of atp.	ribulose bisphosphate (rubp), a substrate of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco), is an inhibitor of rubisco activation by carbamylation if bound to the inactive, noncarbamylated form of the enzyme. the effect of rubisco activase on the dissociation kinetics of rubp bound to this form of the enzyme was examined and characterized with the use of (3)h-labeled rubp and proteins purified from spinach (spinacia oleracea l.) in the absence of rubisco activase and in the presence ...	1992	16669043
organization and topology of photosystem i subunits.	intact spinach (spinacia oleracea) thylakoid membranes were treated with various proteases and photosystem i (psi) complexes were isolated from these membranes to define the membrane topology of specific psi subunits. trypsin treatment caused cleavage of the psi-d and e subunits. thermolysin treatment cleaved the psi-d, e, h, and k subunits, and also caused limited degradation of the reaction center core psi-a and b subunits. pronase treatment produced the most dramatic results as the psi-a and ...	1992	16669018
differential detergent stability of the major light-harvesting complex ii in thylakoids isolated from monocotyledonous and dicotyledonous plants.	a survey of isolated thylakoids from 11 different higher plant species (spinacia oleracea l., pisum sativum l., vicia faba l., brassica napus l., vigna sinensis l., vinca minor l., secale cereale l., triticum aestivum l., triticosecale wittn., hordeum vulgare l., zea mays l.) indicated that the ratio of the oligomeric:monomeric form of the light-harvesting complex ii was twofold higher for the dicots (3.16 +/- 0.35) than the monocots (1.64 +/- 0.25) examined under identical separation procedures ...	1992	16669008
alteration of spinach ribulose-1,5-bisphosphate carboxylase/oxygenase activase activities by site-directed mutagenesis.	site-directed mutagenesis was performed on the 1.6 and 1.9 kilobase spinach (spinacea oleracea) ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco) activase cdnas, encoding the 41 and 45 kilodalton (kd) isoforms of the enzyme, to create single amino acid changes in the putative atp-binding site of rubisco activase (lys-107, gln-109, and ser-112) and in an unrelated cysteine residue (cys-256). replacement of lys-107 with met produced soluble protein with reduced rubisco activase and atpase ...	1992	16668989
developmental history affects the susceptibility of spinach leaves to in vivo low temperature photoinhibition.	room temperature chlorophyll a fluorescence was used to determine the effects of developmental history, developmental stage, and leaf age on susceptibility of spinach to in vivo low temperature (5 degrees c) induced photoinhibition. spinach (spinacia oleracea cv savoy) leaves expanded at cold hardening temperatures (5 degrees c day/night), an irradiance of 250 micromoles per square meter per second of photosynthetic proton flux density, and a photoperiod of 16 hours were less sensitive than leav ...	1992	16668980
k stimulation of atpase activity associated with the chloroplast inner envelope.	studies were conducted to characterize atpase activity associated with purified chloroplast inner envelope preparations from spinach (spinacea oleracea l.) plants. comparison of free mg(2+) and mg.atp complex effects on atpase activity revealed that any mg(2+) stimulation of activity was likely a function of the use of the mg.atp complex as a substrate by the enzyme; free mg(2+) may be inhibitory. in contrast, a marked (one- to twofold) stimulation of atpase activity was noted in the presence of ...	1992	16668922
light-dependent changes in ribulose bisphosphate carboxylase activase activity in leaves.	an assay for the activity of ribulose bisphosphate carboxylase (rubisco) activase in crude leaf extracts was developed. the assay is based on a spectrophotometric assay of rubisco, and activase activity (in nanomoles activated rubisco per minute per milligram chlorophyll) was calculated from the rate of increase in rubisco activity over time. activase activity measurements were made using samples from spinach (spinacia oleracea) leaves undergoing (a) steady-state photosynthesis at various photon ...	1992	16668866
biphasic activation of ribulose bisphosphate carboxylase in spinach leaves as determined from nonsteady-state co(2) exchange.	the activation kinetics of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) following an increase in photon flux density (pfd) were studied by analyzing co(2) assimilation time courses in spinach leaves (spinacia oleracea). when leaves were exposed to 45 minutes of darkness before illumination at 690 micromoles per square meter per second, rubisco activation followed apparent first-order kinetics with a relaxation time of about 3.8 minutes. but when leaves were illuminated for 45 minute ...	1992	16668865
assembly of two subunits of the cyanobacterial photosystem i on the n-side of thylakoid membranes.	photosystem i contains several peripheral membrane proteins that are located on either positive (luminal) or negative (stromal or cytoplasmic) sides of thylakoid membranes of chloroplasts or cyanobacteria. incorporation of two peripheral subunits into photosystem i of the cyanobacterium synechocystis species pcc 6803 was studied using a reconstitution system in which radiolabeled subunits ii (psad) and iv (psae) were synthesized in vitro and incubated with the isolated thylakoid membranes. after ...	1992	16668856
characterization of the activation of membrane-bound and soluble cf(1) by thioredoxin.	the activation of spinach (spinacia oleracea) chloroplast coupling factor 1 (cf(1)) by thioredoxin (thr) was characterized using membrane-bound and soluble cf(1). light generates an electrochemical proton gradient across the thylakoid membrane, which increases the accessibility of the disulfide bond on the gamma-subunit of cf(1) to reduced thr. the proton gradient substantially accelerates the activation of cf(1) compared with thylakoids incubated in the dark with similar concentrations of dithi ...	1992	16668843
some properties of a functional reconstituted plasmalemma h-atpase activated by fusicoccin.	fusicoccin was shown to stimulate the atp-driven, intravesicular acidification of liposomes reconstituted with crude fusicoccin receptors and the h(+)-translocating atpase, both solubilized from maize (zea mays l.) plasma membrane. the present paper reports optimal conditions for dual reconstitution and fusicoccin activation as well as the biochemical characterization of the effect of fusicoccin on this system. fusicoccin stimulation of proton pumping was dependent on ph and fusicoccin concentra ...	1992	16668723
simple determination of the co(2)/o(2) specificity of ribulose-1,5-bisphosphate carboxylase/oxygenase by the specific radioactivity of [c]glycerate 3-phosphate.	a new method is presented for measurement of the co(2)/o(2) specificity factor of ribulose-1,5-bisphosphate carboxylase/oxygenase (rubisco). the [(14)c]3-phosphoglycerate (pga) from the rubisco carboxylase reaction and its dilution by the rubisco oxygenase reaction was monitored by directly measuring the specific radioactivity of pga. (14)co(2) fixation with rubisco occurred under two reaction conditions: carboxylase with oxygenase with 40 micromolar co(2) in o(2)-saturated water and carboxylase ...	1992	16668709
oxidation and reduction of sulfite by chloroplasts and formation of sulfite addition compounds.	after exposing intact chloroplasts isolated from spinach (spinacia oleracea l. cv yates) and capable of photoreducing co(2) at high rates to different concentrations of radioactive sulfite in the light or in the dark, (35)so(2) and h(2) (35)s were removed from the acidified suspensions in a stream of nitrogen. remaining activity could be fractionated into sulfate, organic sulfides, and sulfite addition compounds. when chloroplast suspensions contained catalase, superoxide dismutase and o-acetyls ...	1992	16668703
stromal ph and photosynthesis are affected by electroneutral k and h exchange through chloroplast envelope ion channels.	potassium movement across the limiting membrane of the chloroplast inner envelope is known to be linked to counterex-change of protons. for this reason, k(+) efflux is known to facilitate stromal acidification and the resultant photosynthetic inhibition. however, the specific nature of the chloroplast envelope proteins that facilitate k(+) fluxes, and the biophysical mechanism which links these cation currents to h(+) counterflux, is not characterized. it was the objective of this work to elucid ...	1992	16668693
heterogenous stomatal closure in response to leaf water deficits is not a universal phenomenon.	the extent and occurrence of water stress-induced "patchy" co(2) uptake across the surface of leaves was evaluated in a number of plant species. leaves, while still attached to a plant, were illuminated and exposed to air containing [(14)c]co(2) before autoradiographs were developed. plant water deficits that caused leaf water potential depression to -1.1 megapascals during a 4-day period did result in heterogenous co(2) assimilation patterns in bean (phaseolus vulgaris). however, when the same ...	1992	16668692
decrease of nitrate reductase activity in spinach leaves during a light-dark transition.	in leaves of spinach plants (spinacia oleracea l.) performing co(2) and no(3) (-) assimilation, at the time of sudden darkening, which eliminates photosystem i-dependent nitrite reduction, only a minor temporary increase of the leaf nitrite content is observed. because nitrate reduction does not depend on redox equivalents generated by photosystem i activity, a continuation of nitrate reduction after darkening would result in a large accumulation of nitrite in the leaves within a very short time ...	1992	16668679
herbicide clomazone does not inhibit in vitro geranylgeranyl synthesis from mevalonate.	clomazone reduced the chlorophyll and carotenoid contents of spinach (spinacia oleracea l.), barley (hordeum vulgare l.), velvetleaf (abutilon theophrasti medik.), and soybean (glycine max l. merr.) seedlings. the order of species sensitivity was velvetleaf > spinach > barley > soybean. clomazone (100 micromolar) did not affect the in vitro activities of spinach isopentenyl pyrophosphate isomerase or prenyl transferase. clomazone also did not affect the synthesis of isopentenyl pyrophosphate fro ...	1992	16668657
purification and molecular and immunological characterization of a unique phosphoribulokinase from the green alga selenastrum minutum.	a unique phosphoribulokinase (adp:d-ribulose 5-phosphate 1-phosphotransferase, ec 2.7.1.19) has been purified to homogeneity from the green alga selenastrum minutum. the enzyme has a native molecular mass of about 83 kilodaltons and a native isoelectric point of 5.1. the enzyme consists of two different-sized subunits of 41 and 40 kilodaltons, implying that it is a heterodimer. this is the first report of a eukaryotic heterodimeric phosphoribulokinase. the in vivo existence of two nonidentical s ...	1992	16668652
adp-glucose transport by the chloroplast adenylate translocator is linked to starch biosynthesis.	in organello starch biosynthesis was studied using intact chloroplasts isolated from spinach leaves (spinacia oleracea). immunoblot analysis using a specific antiserum against the mitochondrial adenylate (adp/atp) translocator of neurospora crassa shows the presence of an adenylate translocator protein in the chloroplast envelope membranes, similar to that existing in mitochondria and amyloplasts from cultured cells of sycamore (acer pseudoplatanus). the double silicone oil layer-filtering centr ...	1991	16668585
stromal low temperature compartment derived from the inner membrane of the chloroplast envelope.	leaf discs of four dicotyledonous species, when incubated at temperatures of 4 to 18 degrees c (optimum at 12 degrees c) for 30 or 60 minutes, responded by accumulations of membranes in the chloroplast stroma in the space between the inner membrane of the envelope and the thylakoids. the accumulated membranes, here referred to as the low temperature compartment, were frequently continuous with the envelope membrane and exhibited kinetics of formation consistent with a derivation from the envelop ...	1991	16668584
identification of gibberellins in spinach and effects of light and darkness on their levels.	the endogenous gibberellin (ga) content of spinach (spinacia oleracea) was reinvestigated by combined gas chromatography-mass spectrometry analysis. the 13-hydroxy gas: ga(53), ga(44), ga(19), ga(17), ga(20), ga(5), ga(1), ga(29), and ga(8); the non-3, 13-hydroxy gas: ga(12), ga(15), ga(9), and ga(51); and the 3beta-hydroxy gas: ga(4), ga(7), and ga(34), were identified in spinach extracts by comparing full-scan mass spectra and kovats retention indices with those of reference gas. in addition, ...	1991	16668579
ion relations of symplastic and apoplastic space in leaves from spinacia oleracea l. and pisum sativum l. under salinity.	salt tolerant spinach (spinacia oleracea) and salt sensitive pea (pisum sativum) plants were exposed to mild salinity under identical growth conditions. in order to compare the ability of the two species for extra- and intracellular solute compartmentation in leaves, various solutes were determined in intercellular washing fluids and in aqueously isolated intact chloroplasts. in pea plants exposed to 100 millimolar nacl for 14 days, apoplastic salt concentrations in leaflets increased continuous ...	1991	16668541
purification and characterization of pea cytosolic ascorbate peroxidase.	the cytosolic isoform of ascorbate peroxidase was purified to homogeneity from 14-day-old pea (pisum sativum l.) shoots. the enzyme is a homodimer with molecular weight of 57,500, composed of two subunits with molecular weight of 29,500. spectral analysis and inhibitor studies were consistent with the presence of a heme moiety. when compared with ascorbate peroxidase activity derived from ruptured intact chloroplasts, the purified enzyme was found to have a higher stability, a broader ph optimum ...	1991	16668537
partial purification and characterization of ribulose-1,5-bisphosphate carboxylase/oxygenase large subunit epsilonn-methyltransferase.	the large subunit (ls) of tobacco (nicotiana rustica) ribulose-1,5-bisphosphate carboxylase/oxygenase (ribulose-p(2) carboxylase) contains a trimethyllysyl residue at position 14, whereas this position is unmodified in spinach ribulose-p(2) carboxylase. a protein fraction was isolated from tobacco chloroplasts by rate-zonal centrifugation and anion-exchange fast protein liquid chromatography that catalyzed transfer of methyl groups from s-adenosyl-[methyl-(3)h]-l-methionine to spinach ribulose-p ...	1991	16668531
regulatory and structural properties of the cyanobacterial adpglucose pyrophosphorylases.	adpglucose pyrophosphorylase (ec 2.7.7.27) has been purified from two cyanobacteria: the filamentous, heterocystic, anabaena pcc 7120 and the unicellular synechocystis pcc 6803. the purification procedure gave highly purified enzymes from both cynobacteria with specific activities of 134 (synechocystis) and 111 (anabaena) units per milligram protein. the purified enzymes migrated as a single protein band in sodium dodecyl sulfate-polyacrylamide gel electrophoresis with molecular mass correspondi ...	1991	16668507
surface charge-mediated effects of mg on k flux across the chloroplast envelope are associated with regulation of stromal ph and photosynthesis.	studies of spinacia oleracea l. were undertaken to characterize further how mg(2+) external to the isolated intact chloroplast interacts with stromal k(+), ph, and photosynthetic capacity. data presented in this report were consistent with the previously developed hypothesis that millimolar levels of external, unchelated mg(2+) result in lower stromal k(+), which somehow is linked to stromal acidification. stromal acidification directly results in photosynthetic inhibition. these effects were at ...	1991	16668438
amino acid and sucrose content determined in the cytosolic, chloroplastic, and vacuolar compartments and in the phloem sap of spinach leaves.	amino acid and sucrose contents were analyzed in the chloroplastic, cytosolic, and vacuolar compartments and in the phloem sap of illuminated spinach leaves (spinacia oleracea l.). the determination of subcellular metabolite distribution was carried out by nonaqueous fractionation of frozen and lyophilized leaf material using a novel three-compartment calculation method. the phloem sap was collected by aphid stylets which had been severed by a laser beam. subcellular analysis revealed that the a ...	1991	16668375
effect of microtubule stabilization on the freezing tolerance of mesophyll cells of spinach.	freezing, dehydration, and supercooling cause microtubules in mesophyll cells of spinach (spinacia oleracea l. cv bloomsdale) to depolymerize (me bartolo, jv carter, plant physiol [1991] 97: 175-181). the objective of this study was to determine whether the lt(50) (lethal temperature: the freezing temperature at which 50% of the tissue is killed) of spinach leaf tissue can be changed by diminishing the extent of microtubule depolymerization in response to freezing. also examined was how toleranc ...	1991	16668367
microtubules in mesophyll cells of nonacclimated and cold-acclimated spinach : visualization and responses to freezing, low temperature, and dehydration.	responses of cortical microtubules in spinach (spinacia oleracea l. cv bloomsdale) mesophyll cells to freezing, thawing, supercooling, and dehydration were assessed. microtubules were visualized using a modified procedure for indirect immunofluorescence microscopy. leaf sections of nonacclimated and cold-acclimated spinach were slowly frozen to various temperatures, fixed while frozen, and microtubules immunolabelled. both nonacclimated and cold-acclimated cells exhibited nearly complete microtu ...	1991	16668366
solubilization, partial purification, and reconstitution of the glycolate/glycerate transporter from chloroplast inner envelope membranes.	the glycolate/glycerate transporter of spinach (spinacia oleracea l.) chloroplast inner envelope membranes was solubilized by treatment of the membranes with sodium cholate. mixtures of the cholate extracts and soy asolectin were subjected to gel filtration to remove the detergent. the reconstituted vesicles were frozen, thawed, and sonicated in a buffer that contained 10 millimolar d-glycerate and, usually, [(3)h]sucrose as an internal space indicator. the dilution of the vesicles into a medium ...	1991	16668298
regulation by ca of a cytosolic fructose-1,6-bisphosphatase from spinach leaves.	cytosolic fructose-1,6-bisphosphatase from spinach (spinacia oleracea l.) leaves was purified over 1700-fold. the final preparation was specific for fructose-1,6-bisphosphate in the presence of either mg(2+) or mn(2+), and was free of interfering enzyme activities. ca(2+) was an effector of fructose-1,6-bisphosphatase activity, and showed different kinetics, depending on whether mg(2+) or mn(2+) was used as cofactor. in the presence of 5 millimolar mg(2+), ca(2+) appeared as activator or as inhi ...	1991	16668293
compartmentation studies on spinach leaf peroxisomes : evidence for channeling of photorespiratory metabolites in peroxisomes devoid of intact boundary membrane.	in concurrence with earlier results, the following enzymes showed latency in intact spinach (spinacia oleracea l.) leaf peroxisomes: malate dehydrogenase (89%), hydroxypyruvate reductase (85%), serine glyoxylate aminotransferase (75%), glutamate glyoxylate aminotransferase (41%), and catalase (70%). in contrast, glycolate oxidase was not latent. aging of peroxisomes for several hours resulted in a reduction in latency accompanied by a partial solubilization of the above mentioned enzymes. the ex ...	1991	16668283
acyl carrier protein is conjugated to glutathione in spinach seed.	acyl carrier protein (acp) contains an essential sulfhydryl group in its phosphopantetheine prosthetic group. we have investigated the state of this sulfhydryl in developing and mature spinach seed (spinacia oleracea). seed extracts were separated on sodium dodecyl sulfate or native polyacrylamide gels, blotted to nitrocellulose, and probed with antibodies raised against spinach acp-i. in extracts of mature seeds prepared with reducing agents, acp-ii migrated as a single major band, whereas extr ...	1991	16668278
symport of proton and sucrose in plasma membrane vesicles isolated from spinach leaves.	the mechanism of sucrose transport was investigated in plasma membrane (pm) vesicles isolated from spinach (spinacia oleracea l.) leaves. pm vesicles were isolated by aqueous two-phase partitioning and were equilibrated in ph 7.8 buffer containing k(+). the vesicles rapidly accumulated sucrose in the presence of a transmembrane ph gradient (deltaph) with external ph set at 5.8. the uptake rate was slow at ph 7.8. the k(+)-selective ionophore, valinomycin, stimulated uptake in the presence of a d ...	1991	16668230
spinach leaf acetyl-coenzyme a synthetase: purification and characterization.	acetyl-coenzyme a (coa) synthetase was purified 364-fold from leaves of spinach (spinacia oleracea l.) using ammonium sulfate fractionation followed by ion exchange, dye-ligand, and gel permeation chromatography. the final specific activity was 2.77 units per milligram protein. the average m(r) value of the native enzyme was about 73,000. the michaelis constants determined for mg-atp, acetate, and coenzyme a were 150, 57, and 5 micromolar, respectively. the purified enzyme was sensitive to subst ...	1991	16668197
rapid modulation of spinach leaf nitrate reductase by photosynthesis : ii. in vitro modulation by atp and amp.	assimilatory nitrate reductase activity (nra) in crude spinach leaf (spinacia oleracea) extracts undergoes rapid changes following fluctuations in photosynthesis brought about by changes in external co(2) or by water stress (wm kaiser, e brendle-behnisch [1991] plant physiol 96:363-367). a modulation of nra sharing several characteristics (stability, response to mg(2+) or ca(2+), kinetic constants) with the in vivo modulation was obtained in vitro by preincubating desalted leaf extracts with phy ...	1991	16668195
rapid modulation of spinach leaf nitrate reductase activity by photosynthesis : i. modulation in vivo by co(2) availability.	it has been shown recently that in spinach leaves (spinacia oleracea) net photosynthesis and nitrate reduction are closely linked: when net photosynthesis was low because of stomatal closure, rates of nitrate reduction decreased (wm kaiser, j förster [1989] plant physiol 91: 970-974). here we present evidence that photosynthesis regulates nitrate reduction by modulating nitrate reductase activity (nra, ec 1.6.6.1). when spinach leaves were exposed to low co(2) in the light, extractable nra decli ...	1991	16668194
protection of tryptic-sensitive sites in the large subunit of ribulosebisphosphate carboxylase/oxygenase by catalysis.	limited tryptic proteolysis of spinach (spinacia oleracea) ribulose bisphosphate carboxylase/oxygenase (ribulose-p(2) carboxylase) resulted in the ordered release of two adjacent n-terminal peptides from the large subunit, and an irreversible, partial inactivation of catalysis. the two peptides were identified as the n-terminal tryptic peptide (acetylated pro-3 to lys-8) and the penultimate tryptic peptide (ala-9 to lys-14). kinetic comparison of hydrolysis at lys-8 and lys-14, enzyme inactivati ...	1991	16668178
measurement of 2-carboxyarabinitol 1-phosphate in plant leaves by isotope dilution.	the level of 2-carboxyarabinitol 1-phosphate (ca1p) in leaves of 12 species was determined by an isotope dilution assay. (14)c-labeled standard was synthesized from [2-(14)c]carboxyarabinitol 1,5-bisphosphate using acid phosphatase, and was added at the initial point of leaf extraction. leaf ca1p was purified and its specific activity determined. ca1p was found in dark-treated leaves of all species examined, including spinach (spinacea oleracea), wheat (triticum aestivum), arabidopsis thaliana, ...	1991	16668153
biosynthesis and desaturation of prokaryotic galactolipids in leaves and isolated chloroplasts from spinach.	mono- and digalactosyldiacylglycerol (mgdg and dgdg) were isolated from the leaves of sixteen 16:3 plants. in all of these plant species, the sn-2 position of mgdg was more enriched in c(16) fatty acids than sn-2 of dgdg. the molar ratios of prokaryotic mgdg to prokaryotic dgdg ranged from 4 to 10. this suggests that 16:3 plants synthesize more prokaryotic mgdg than prokaryotic dgdg. in the 16:3 plant spinacia oleracea l. (spinach), the formation of prokaryotic galactolipids was studied both in ...	1991	16668143
studies on the system regulating proton movement across the chloroplast envelope : effects of atpase inhibitors, mg, and an amine anesthetic on stromal ph and photosynthesis.	studies were undertaken to further characterize the spinach (spinacea oleracea) chloroplast envelope system, which facilitates h(+) movement into and out of the stroma, and, hence, modulates photosynthetic activity by regulating stromal ph. it was demonstrated that high envelope-bound mg(2+) causes stromal acidification and photosynthetic inhibition. high envelope-bound mg(2+) was also found to necessitate the activity of a digitoxinand oligomycin-sensitive atpase for the maintenance of high str ...	1991	16668116
redox transfer across the inner chloroplast envelope membrane.	in leaves of spinach plants (spinacia oleracea l.) grown in ambient co(2) the subcellular contents of adenylates, pyridine nucleotides, 3-phosphoglycerate, dihydroxyacetone phosphate, malate, glutamate, 2-oxoglutarate, and aspartate were assayed in the light and in the dark by nonaqueous fractionation technique. from the concentrations of nadp and nadph determined in the chloroplast fraction of illuminated leaves the stromal nadph to nadp ratio is calculated to be 0.5. for the cytosol a nadh to ...	1991	16668101
dissipation of the proton electrochemical potential in intact and lysed chloroplasts : i. the electrical potential.	effective ionophore:chlorophyll ratios were determined for various ionophores that decrease the electrical potential across thylakoid membranes in intact and hypo-osmotically lysed chloroplasts isolated from spinach (spinacia oleracea). the efficacy of gramicidin d, valinomycin, carbonylcyanide m-chlorophenylhydrazone, and dicyclohexano-18-crown-6 in collapsing the electrical potential was determined spectrophotometrically by the decay half-time of the absorbance change at 518 nanometers induced ...	1991	16668015
nonsteady-state photosynthesis following an increase in photon flux density (pfd) : effects of magnitude and duration of initial pfd.	the response of photosynthesis to an increase in photon flux density (pfd) from low to higher pfd was investigated using spinach (spinacia oleracea l.). the time-course for this response was qualitatively similar to that observed for a dark-to-high-pfd transition, showing an initial, rapid increase in photosynthesis over the first minute or so, followed by a slower increase lasting 5 to 10 minutes. this slow increase was approximately exponential and could be linearized using a semilogarithmic p ...	1991	16668012
formation of the fe-s cluster of ferredoxin in lysed spinach chloroplasts.	in vitro formation of the (35)s-labeled fe-s cluster of ferredoxin (fd) has been achieved by incubating apo-fd and [(35)s]cysteine with osmotically lysed chloroplasts of spinach (spinacia oleracea). correct integration of the (35)s-labeled fe-s cluster into fd was verified on the basis of the following: (a) under nondenaturing conditions, (35)s-labeled holo-fd showed the same electrophoretic mobility as authentic holo-fd; (b) (35)s-labeled holo-fd showed an ability to bind fd-nadp(+) reductase; ...	1991	16667987
nadh-ferricyanide reductase of leaf plasma membranes : partial purification and immunological relation to potato tuber microsomal nadh-ferricyanide reductase and spinach leaf nadh-nitrate reductase.	plasma membranes obtained by two-phase partitioning of microsomal fractions from spinach (spinacea oleracea l. cv medania) and sugar beet leaves (beta vulgaris l.) contained relatively high nadh-ferricyanide reductase and nadh-nitrate reductase (nr; ec 1.6.6.1) activities. both of these activities were latent. to investigate whether these activities were due to the same enzyme, plasma membrane polypeptides were separated with sds-page and analyzed with immunoblotting methods. antibodies raised a ...	1991	16667982
inactivation of highly activated spinach leaf sucrose-phosphate synthase by dephosphorylation.	spinach (spinacia oleracea l.) leaf sucrose-phosphate synthase (sps) can be phosphorylated and inactivated in vitro with [gamma-(32)p]atp (jla huber, sc huber, th nielsen [1989] arch biochem biophys 270: 681-690). thus, it was surprising to find that sps, extracted from leaves fed mannose in the light to highly activate the enzyme, could be inactivated in an atp-independent manner when desalted crude extracts were preincubated at 25 degrees c before assay. the "spontaneous" inactivation involved ...	1991	16667968
isolation and characterization of a cdna coding for pea chloroplastic carbonic anhydrase.	using a polyclonal antibody generated against the purified pea (pisum sativum) carbonic anhydrase (ca) monomeric species, we have isolated and characterized a cdna coding for this enzyme. protein sequence analysis was used to confirm the identity of the clone. the presence of a large transit peptide suggests that ca is transported into the chloroplast and then processed to the mature size of approximately 26 kilodaltons. northern hybridization, using the ca cdna as a probe of total leaf rna, rev ...	1991	16667962
isolation of a cdna clone for spinach lipid transfer protein and evidence that the protein is synthesized by the secretory pathway.	a cdna clone encoding a nonspecific lipid transfer protein from spinach (spinacia oleracea) was isolated by probing a library with synthetic oligonucleotides based on the amino acid sequence of the protein. determination of the dna sequence indicated a 354-nucleotide open reading frame which encodes a 118-amino acid residue polypeptide. the first 26 amino acids of the open reading frame, which are not present in the mature protein, have all the characteristics of a signal sequence which is norma ...	1991	16667945
roles of atp and nadph in formation of the fe-s cluster of spinach ferredoxin.	ferredoxin (fd) in higher plants is encoded by a nuclear gene, synthesized in the cytoplasm as a larger precursor, and imported into the chloroplast, where it is proteolytically processed, and assembled with the [2fe-2s] cluster. the final step in the biosynthetic pathway of fd can be analyzed by a reconstitution system composed of isolated chloroplasts and [(35)s]cysteine, in which [(35)s]sulfide and iron are incorporated into fd to build up the (35)s-labeled fe-s cluster. although a lysed chlo ...	1991	16667935
primary structure of chlamydomonas reinhardtii ribulose 1,5-bisphosphate carboxylase/oxygenase activase and evidence for a single polypeptide.	immunoblot analysis of ribulose 1,5-bisphosphate carboxylase/oxygenase (rubisco) activase from the green alga chlamydomonas reinhardtii indicated the presence of a single polypeptide. this observation contrasts with the spinacea oleracea (spinach) and arabidopsis thaliana proteins, in which two polypeptide species are generated by alternative pre-mrna splicing. a chlamydomonas rubisco activase cdna clone containing the entire coding region was isolated and sequenced. the open reading frame encod ...	1990	16667924
effect of growth temperature and temperature shifts on spinach leaf morphology and photosynthesis.	the growth kinetics of spinach plants (spinacia oleracea l. cv savoy) grown at 5 degrees c or 16 degrees c were determined to allow us to compare leaf tissues of the same developmental stage rather than chronological age. the second leaf pairs reached full expansion at a plant age of 32 and 92 days for the 16 degrees c and 5 degrees c plants, respectively. growth at 5 degrees c resulted in an increased leaf area, dry weight, dry weight per area, and leaf thickness. despite these changes, pigment ...	1990	16667923
polysaccharide fraction from higher plants which strongly interacts with the cytosolic phosphorylase isozyme : i. isolation and characterization.	from leaves of spinacia oleracea l. or from pisum sativum l. and from cotyledons of germinating pea seeds a high molecular weight polysaccharide fraction was isolated. the apparent size of the fraction, as determined by gel filtration, was similar to that of dextran blue. following acid hydrolysis the monomer content of the polysaccharide preparation was studied using high pressure liquid and thin layer chromatography. glucose, galactose, arabinose, and ribose were the main monosaccharide compou ...	1990	16667877
d-glucosone and l-sorbosone, putative intermediates of l-ascorbic acid biosynthesis in detached bean and spinach leaves.	d-[6-(14)c]glucosone that had been prepared enzymically from d-[6-(14)c]glucose was used to compare relative efficiencies of these two sugars for l-ascorbic acid (aa) biosynthesis in detached bean (phaseolus vulgaris l., cv california small white) apices and 4-week-old spinach (spinacia oleracea l., cv giant noble) leaves. at tracer concentration, (14)c from glucosone was utilized by spinach leaves for aa biosynthesis much more effectively than glucose. carbon-14 from [6-(14)c]glucose underwent ...	1990	16667861
conversion of l-sorbosone to l-ascorbic acid by a nadp-dependent dehydrogenase in bean and spinach leaf.	an nadp-dependent dehydrogenase catalyzing the conversion of l-sorbosone to l-ascorbic acid has been isolated from phaseolus vulgaris l. and spinacia oleracea l. and partially purified. it is stable at -20 degrees c for up to 8 months. molecular masses, as determined by gel filtration, were 21 and 29 kilodaltons for bean and spinach enzymes, respectively. k(m) for sorbosone were 12 +/- 2 and 18 +/- 2 millimolar and for nadp(+), 0.14 +/- 0.05 and 1.2 +/- 0.5 millimolar, for bean and spinach, resp ...	1990	16667860
localization of atp sulfurylase and o-acetylserine(thiol)lyase in spinach leaves.	the intracellular compartmentation of atp sulfurylase and o-acetylserine(thiol)lyase in spinach (spinacia oleracea l.) leaves has been investigated by isolation of organelles and fractionation of protoplasts. atp sulfurylase is located predominantly in the chloroplasts, but is also present in the cytosol. no evidence was found for atp sulfurylase activity in the mitochondria. two forms of atp sulfurylase were separated by anion-exchange chromatography. the more abundant form is present in the ch ...	1990	16667839
free fatty acids regulate two galactosyltransferases in chloroplast envelope membranes isolated from spinach leaves.	effects of mgcl(2) and free fatty acids (ffa) on galactolipid:galactolipid galactosyltransferase (gggt) and udp-galactose: 1,2-diacylglycerol galactosyltransferase (udgt) in chloroplast envelope membranes isolated from spinach (spinacia oleracea l.) leaves were examined. gggt activity was sigmoidally stimulated by mgcl(2) with a saturated concentration of more than 5 millimolar. free alpha-linolenic acid (18:3) caused a drastic increase in gggt activity under limiting concentrations of mgcl(2), ...	1990	16667779
pathway for the synthesis of triacylglycerols from monogalactosyldiacylglycerols in ozone-fumigated spinach leaves.	when the upper leaf surface of spinach (spinacia oleracea l.) plants was treated with [1-(14)c]acetate and grown for 2 days, (14)c was effectively incorporated into acyl moieties of leaf lipids in ratios approximately their composition by mass. fumigation of the plants with ozone (0.5 microliter per liter) caused a redistribution of (14)c among lipid classes, i.e. a marked increase of (14)c content in triacylglycerol (tg) and 1,2-diacylglycerol (1,2-dg) and a decrease of label in monogalactosyld ...	1990	16667778
conversion of monogalactosyldiacylglycerols to triacylglycerols in ozone-fumigated spinach leaves.	molecular species and fatty acid distribution of triacylglycerol (tg) accumulated in spinach (spinacia oleracea l.) leaves fumigated with ozone (0.5 microliter per liter) were compared with those of monogalactosyldiacylglycerol (mgdg). analysis of positional distribution of the fatty acids in mgdg and the accumulated tg by the enzymatic digestion method showed that hexadecatrienoate (16:3) was restricted to sn-2 position of the glycerol backbone in both mgdg and tg, whereas alpha-linolenate (18: ...	1990	16667777
determination of oxygen emission and uptake in leaves by pulsed, time resolved photoacoustics.	pulsed, time resolved photoacoustics has sufficient sensitivity to determine oxygen emission and uptake by single turnover flashes to leaves. the advantage over previous methodologies is that when combined with single turnover flashes the kinetics of the thermal and the gas signals can be resolved to 0.1 millisecond and separated. the s-state oscillations of oxygen formation are readily observed. the gas signal from common spongy leaves such as spinach (spinacia sp.), japanese andromeda (pieris ...	1990	16667697
involvement of ferredoxin in desaturation of lipid-bound oleate in chloroplasts.	intact spinach (spinacia oleracea) chloroplasts, pulse-labeled with [(14)c]acetate, desaturate newly formed fatty acids as ester groups of monogalactosyl diacylglycerol in a subsequent chase in the dark. rupture of pulse-labeled chloroplasts by addition of a detergent solution 3-([3-cholamidopropyl]dimethylammonio)-1-propane sulfonate preserves part of this desaturation activity. direct addition of different free fatty acids together with appropriate cofactors to detergent-ruptured chloroplasts ...	1990	16667689
activity of ribulose 1,5-bisphosphate carboxylase oxygenase as a function of storage conditions.	optimal storage conditions to retain ribulose 1, 5-bisphosphate carboxylase/oxygenase (rubisco) activity were investigated. the soluble spinach (spinacia oleracea) enzyme was pretreated with its activators, mg(2+) and hco(3) (-), and then stored for up to 30 days at 4 or -18 degrees c or in liquid n(2). cold inactivation and conformational changes were suggested to be involved during rubisco storage in the cold, leading to its inactivation. pretreatment of the enzyme with mg(2+) and co(2) and su ...	1990	16667648
cause for dark, chilling-induced inactivation of photosynthetic oxygen-evolving system in cucumber leaves.	effects on oxygen evolution of the storage of detached cucumber (cucumis sativus) leaves at 0 degrees c in the dark were investigated with thylakoids and oxygen-evolving photosystem ii membranes isolated from stored leaves. the cold and dark treatment of leaves selectively inactivated electron transport on the oxidizing side of photosystem ii. photosystem ii membranes isolated from treated leaves were largely depleted of two proteins of 20 and 14 kilodaltons, which correspond to the extrinsic 23 ...	1990	16667624
biosynthesis of digalactosyldiacylglycerol in plastids from 16:3 and 18:3 plants.	intact chloroplasts isolated from leaves of eight species of 16:3 and 18:3 plants and chromoplasts isolated from narcissus pseudonarcissus l. flowers synthesize galactose-labeled mono-, di-, and trigalactosyldiacylglycerol (mgdg, dgdg, and tgdg) when incubated with udp-[6-(3)h]galactose. in all plastids, galactolipid synthesis, and especially synthesis of dgdg and tgdg, is reduced by treatment of the organelles with the nonpenetrating protease thermolysin. envelope membranes isolated from thermo ...	1990	16667615
purification and characterization of a ferredoxin-nadp oxidoreductase-like enzyme from radish root tissues.	an enzyme able to reduce cytochrome c via ferredoxin in the presence of nadph, was isolated, purified from radish (raphanus sativus var acanthiformis cultivar miyashige) roots and characterized. the enzyme was purified by deae-cellulose, blue-cellulofine, ferredoxin-sepharose 4b, and sephadex g-100 column chromatography. molecular mass of the enzyme was estimated to be 33,000 and 35,000 daltons by sephadex g-100 gel filtration and sds-page, respectively. its absorption spectrum suggested that th ...	1990	16667598
carbon metabolism in spinach leaves as affected by leaf age and phosphorus and sulfur nutrition.	spinach (spinacea oleracea) plants were grown either continuously on complete nutrient solutions or for 2 weeks on media deficient in phosphate or sulfate. to characterize leaf carbohydrate metabolism, levels of phosphorylated intermediates, activities of enzymes involved in photosynthetic carbon metabolism, contents of soluble and acid hydrolyzable sugars were measured in leaves differing in age and mineral status and related to leaf rates of photosynthesis and assimilate partitioning. concentr ...	1990	16667581
sulfhydryl reagents and energy-linked reactions in monocot thylakoids.	monofunctional maleimides have been used to covalently modify the coupling factor protein of monocot thylakoid membranes. as with dicot thylakoids, incubation of the monocot thylakoids with maleimides in the light but not in the dark results in inhibition of both atp synthesis and hydrolysis. in the dark, sites on the gamma and epsilon subunits of maize zea mays coupling factor 1 are modified after incubation of maize mesophyll thylakoids with the fluorescent maleimide n-(anilinonaphthyl-4) male ...	1990	16667548
thermal dependence of the apparent k(m) of glutathione reductases from three plant species.	the thermal dependencies of the apparent k(m) of the glutathione reductases from spinach (spinacia oleracea l.) corn (zea mays l.), and cucumber (cucumis sativus l.) were determined. the apparent k(m) of the enzymes were found to vary up to 9-fold between 12.5 and 45 degrees c. values of the apparent k(m) in excess of 200% of the observed minimum are suggested to be detrimental to the normal function of the enzyme. we propose the term "thermal kinetic window" to describe to the range of temperat ...	1990	16667543
shikimate kinase from spinach chloroplasts : purification, characterization, and regulatory function in aromatic amino acid biosynthesis.	shikimate kinase was purified to near homogenity from spinach spinacia oleracea l. chloroplasts and found to consist of a single 31 kilodalton polypeptide. the purified enzyme was unstable, but could be stabilized by a variety of added proteins, including oxidized and reduced thioredoxins. whereas the isolated enzyme was stimulated by mono- and dithiol reagents, the enzyme in intact chloroplasts was unaffected by added thiols and showed only minor response to dark/light transitions. these result ...	1990	16667533
isolation and characterization of the cytosolic and chloroplastic 3-phosphoglycerate kinase from spinach leaves.	the cytosol and chloroplast 3-phosphoglycerate kinases (3-pgk) from spinach (spinacia oleracea l.) were purifled to apparent homogeneity. the procedure included a conventional anion-exchange chromatography on deae-cellulose and mainly a series of hplc columns. the charge differences of the two isoenzymes were so small that separation was only successful by anion-exchange chromatography on a hplc synchropak ax 300 column. the portion of the two isoenzmyes in leaf tissue was estimated as 5% and 95 ...	1990	16667463
status of the substrate binding sites of ribulose bisphosphate carboxylase as determined with 2-c-carboxyarabinitol 1,5-bisphosphate.	the properties of the tight and specific binding of 2-c-carboxy-d-arabinitol 1,5-bisphosphate (cabp), which occurs only to reaction sites of ribulose 1,5-bisphosphate carboxylase (rubisco) that are activated by co(2) and mg(2+), were studied. with fully active purified spinach (spinacia oleracea) rubisco the rate of tight binding of [(14)c]cabp fit a multiple exponential rate equation with half of the sites binding with a rate constant of 40 per minute and the second half of the sites binding at ...	1990	16667442
chlamydomonas reinhardtii phosphoribulokinase : sequence, purification, and kinetics.	the sequence and kinetic properties of phosphoribulokinase purified from chlamydomonas reinhardtii were determined and compared with the spinach (spinacea oleracea) enzyme. chlamydomonas phosphoribulokinase was purified to apparent homogeneity, with a specific activity of 410 micromoles per minute per milligram. polyclonal antibodies to the purified protein were used to isolate a chlamydomonas cdna clone, which, upon sequencing, was found to contain the entire coding region. the transit peptide ...	1990	16667433
nitrite photoreduction in vivo is inhibited by oxygen.	it was hypothesized previously that an o(2) inhibition of no(2) (-) photoreduction would reflect a competition between o(2) and no(2) (-) for electrons from ferredoxin at the site of plastid nitrite reductase. in order to test this in vivo, intact spinach (spinacia oleracea l.) leaf chloroplast and mesophyll cell isolates held in high light were aerated with streams of 20% o(2)/80% n(2) (250 micromolar o(2) in aqueous solution) or, alternatively, streams of 100% n(2). bicarbonate plus co(2) and ...	1990	16667362
oxidation versus reductive detoxification of so(2) by chloroplasts.	intact chloroplasts isolated from spinach (spinacia oleracea l. cv yates) both oxidized and reduced added sulfite in the light. oxidation was fast only when endogenous superoxide dismutase was inhibited by cyanide. it was largely suppressed by scavengers of oxygen radicals. after addition of o-acetylserine, chloroplasts reduced sulfite to cysteine and exhibited sulfite-dependent oxygen evolution. cysteine synthesis from sulfite was faster than from sulfate. the results are discussed in relation ...	1990	16667358
purification by immunoadsorption and immunochemical properties of nadp-dependent malic enzymes from leaves of c(3), c(4), and crassulacean acid metabolism plants.	nadp:malic enzyme from corn (zea mays l.) leaves was purified by conventional techniques to apparent homogeneity as judged by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. antibodies raised against this protein in rabbits were purified, coupled covalently to protein a-sepharose cl-4b, and used as an immunoaffinity resin to purify the nadp:malic enzymes of the c(3) plants spinach (spinacia oleracea l.) and wheat (triticum aestivum l.), of the crassulacean acid metabolism (cam) plant ...	1990	16667339
on the regulation of spinach nitrate reductase.	a coupled assay has been worked out to study spinach (spinacea oleracea l.) nitrate reductase under low, more physiological concentrations of nadh. in this assay the reduction of nitrate is coupled to the oxidation of malate catalyzed by spinach nad-malate dehydrogenase. the use of this coupled system allows the assay of nitrate reductase activity at steady-state concentrations of nadh below micromolar. we have used this coupled assay to study the kinetic parameters of spinach nitrate reductase ...	1990	16667335
subcellular compartmentation of uridine nucleotides and nucleoside-5' -diphosphate kinase in leaves.	the subcellular compartmentation of nucleoside diphosphate kinase (ec 2.7.4.6) and the uridine nucleotides has been studied in leaves. membrane filtration of barley (hordeum vulgare l.) leaf mesophyll protoplasts and differential centrifugation of spinach (spinacia oleracea l.) leaf extracts showed that about half the nucleoside diphosphate kinase is present in the cytosol. the activity is adequate to account for the turnover of utp and udp during photosynthetic sucrose synthesis. nonaqueous den ...	1990	16667327
identification of the large subunit of ribulose 1,5-bisphosphate carboxylase/oxygenase as a substrate for transglutaminase in medicago sativa l. (alfalfa).	extracts prepared from floral meristematic tissue of alfalfa (medicago sativa l.) were investigated for expression of the enzyme transglutaminase in order to identify the major protein substrate for transglutaminase-directed modifications among plant proteins. the large polymorphic subunits of ribulose 1,5-bisphosphate carboxylase/oxygenase in alfalfa, with molecular weights of 52,700 and 57,600, are major substrates for transglutaminase in these extracts. this was established by: (a) covalent c ...	1990	16667270
spinach chloroplastic carbonic anhydrase: nucleotide sequence analysis of cdna.	we have determined the nucleotide sequence of a cdna encoding spinach (spinacia oleracea) chloroplastic carbonic anhydrase (ca). the open reading frame encodes a protein consisting of a transit peptide and a mature ca protein with a predicted mass of 24, 116 daltons. this represents the first report of a nucleotide sequence of a plant ca.	1990	16667262