| affinity chromatography of trypsin and related enzymes. i. preparation and characteristics of an affinity adsorbent containing tryptic peptides from protamine as ligands. | an absorbent for the affinity chromatography of trypsin ec 3.4.21.4 (ap sepharose) was prepared. the ligand was a mixture of oligopeptides (mainly di- and tripeptides) containing l-arginine as carboxyl termini, and was obtained from a tryptic digest of protamine. trypsin was absorbed at relatively low ph (7-4), but was not absorbed at the optimum ph of catalysis (8.2). this was clearly explained on the basis of the ph dependence of the interaction of trypsin with its products. inactivated trypsi ... | 1975 | 2582 |
| mitochondrial malate dehydrogenase of bovine cerebrum. characterization and mechanisms of inhibition by silver ions. | attempts were made to characterize mitochondrial malate dehydrogenase l-malate: nad+ oxidoreductase, ec 1.1.1.37 (m-mdh) purified from bovine cerebrum and to elucidate the mechanisms responsible for inhibition of the enzymic activity by ag+. the molecular weights of the native enzyme and its subunits were 54,000-55,000 and 30,000-32,000, respectively. in general, the physiochemical and catalytic properties of bovine cerebral m-mdh was not very different from those of other corresponding mammalia ... | 1975 | 2592 |
| the binding of catecholamines to the serum proteins of the rat and the domestic fowl. | | 1975 | 3370 |
| bilateral cryptorchidism in a bull. | clinical and pathological observations were made on a case of bilateral cryptorchidism in a bull. sexual libido could not be assessed because the bull was housed alone. the location of the intraabdominal testes indicated that surgical castration would necessitate a flank laparotomy incision. | 1976 | 3387 |
| effect of monensin fed with forage on digestion and the ruminal ecosystem of steers. | | 1976 | 2571 |
| quenching of tryptophanyl fluorescence of human growth hormone by iodide. | quenching of tryptophanyl fluorescence of human growth hormone by i- followed saturation kinetics and was abolished by kscn. in the presence of 6 m guanidine hydrochloride quenching was linear between 0 to 0.2 m ki. these results suggest that i- quenched the fluorescence of the native hormone by binding at or near the single tryptophanyl residue. quenching by 0.1 m ki decreased exponentially with increasing concentrations of human and bovine growth hormones. acidification did not have a signific ... | 1976 | 3284 |
| inhibition by superoxide dismutase of methemoglobin formation from oxyhemoglobin. | the formation of methemoglobin from oxyhemoglobin in a solution containing photoreduced riboflavin and oxygen was inhibited by superoxide dismutase. the rate of the reaction was ph-dependent in the range of 6.8 to 7.8, increasing as the ph was reduced. inhibition by superoxide dismutase was enhanced as the edta concentration increased and was dependent on enzymatic activity. under conditions in which superoxide dismutase inhibition was incomplete, catalase inhibited the reaction but mannitol had ... | 1976 | 2597 |
| correlation of the kinetics of electron transfer activity of various eukaryotic cytochromes c with binding to mitochondrial cytochrome c oxidase. | 1. a detailed study of cytochrome c oxidase activity with keilin-hartree particles and purified beef heart enzyme, at low ionic strength and low cytochrome c concentrations, showed biphasic kinetics with apparent km1 = 5 x 10(-8) m, and apparent km2 = 0.35 to 1.0 x 10(-6) m. direct binding studies with purified oxidase, phospholipid-containing as well as phospholiptaining aid-depleted, demonstrated two sites of interaction of cytochrome c with the enzyme, with kd1 less than or equal to 10(-7) m ... | 1976 | 2600 |
| identification of albumin as the serum factor essential for the growth of activated human lymphocytes. | albumin from human, bovine, or rabbit serum supported the growth of concanavalin a-stimulated human thymus-derived lymphocytes equally well. this activity was completely abolished by pepsin digestion. it was shown for bovine serum albumin that the albumin molecule itself, and neither an impurity nor a factor bound to albumin was essential for the growth of lymphocytes. this conclusion was based on observations that the growth-promoting activity could not be removed from albumin, and that the spe ... | 1976 | 2610 |
| cathepsin, phosphoprotein-phosphatase and acid phosphatase in the soluble fraction of the cattle brain cortex: purification and properties (author's transl). | cattle brain cortex was homogenised in 0, 29 mol/1 sucrose and centrifuged at 101 000 x g. the supernatant contains the majority of 3 enzymes participating in protein turnover: cathepsin (ec 3.4.4.23), phosphoprotein phosphatase (ec 3.1.3.16) and acid phosphatase (ec 3.1.3.2). they were separated by chromatography on sephadex g 200 in neutral buffer. the cathepsin was purified up to 380 fold by gel filtration on sephadex and column electrophoresis. the ph optimum of cathepsin was 5.7. at 37 degr ... | 1976 | 2648 |
| isolation from bovine brain of a fraction containing capillaries and a fraction containing membrane fragments of the choroid plexus. | combined differential and density gradient centrifugation was used for the isolation of a capillary-rich fraction from the cerebral cortex and a brush border containing fraction from the bovine choroid plexus. the activities of gamma-glutamyl transpeptidase and several other marker enzymes were monitored during the fractionation procedure. electron microscopic examination showed a membrane-rich fraction in the choroid plexus high in the gamma-glutamyl transpeptidase and 5'-nucleotidase activitie ... | 1976 | 2650 |
| synthesis and enzymic activity of some novel xanthine oxidase inhibitors. 3-substituted 5,7-dihydroxypyrazolo(1,5-alpha)pyrimidines. | a series of 3-substituted 5,7-dihydroxypyrazolo1,5-alphapyrimidines containing various aromatic phenyl- (3e), 3-pyridyl- (3f), p-bromophenyl- (3g), p-chlorophenyl- (3h), p-acetamidophenyl- (3i), p-tolyl- (3j), m-tolyl- (3k), 3,4-methylenedioxyphenyl- (3m), or naphthyl- (3n) or nonaromatic hydrogen- (3a), nitro- (3b), bromo- (3c), or chloro- (3d) substituents in the 3 position was synthesized and tested as inhibitors of xanthine oxidase. the compounds (3a-m) were synthesized by condensation of th ... | 1976 | 2778 |
| purification of tyrosine hydroxylase from pheochromocytoma tumors. | | 1976 | 2828 |
| isoenzymes of soluble and membrane-bound acetylcholinesterase in boine splanchnic nerve and adrenal medulla. | | 1975 | 2915 |
| release of acetylcholinesterase into the perfusate from the ox adrenal gland. | | 1975 | 2916 |
| a possible structural basis for the extracellular release of acetylcholinesterase. | | 1975 | 2917 |
| synthesis of 5-substituted isophthalic acids and competitive inhibition studies with bovine liver glutamate dehydrogenase. | isophthalic acid, 5-carboxy-, 5-hydroxy-, 5-methoxy-, 5-fluoro-, 5-bromo-, 5-cyano-, and 5-methylisophthalic acid were inhibitors competitive with l-glutamate for bovine liver glutamate dehydrogenase. the extent of inhibition by the derived compounds was not much greater than that obtained with the parent compound, isophthalic acid. a plot of pki versus ph showed the presence of an ionizable group (pka 7.4-7.8) at the enzyme active site which interacted with the substitutent at the 5 position of ... | 1976 | 2935 |
| distribution of prostaglandin e 9-ketoreductase and nad+-dependent and nadp+-dependent 15-hydroxyprostaglandin dehydrogenase in the renal cortex and medulla of various species. | regional distributions of pge 9-ketoreductase and 15-hydroxy-prostaglandin dehydrogenase were examined in the cytoplasmic fractions from the kidneys of seven species. all species contained an nadph-dependent reductase, as well as nad+- and nadp+-dependent dehydrogenases in both cortex and medulla. a previously unrecognized cytoplasmic nadh-dependent pge 9-ketoreductase was also detected in the cortex and medulla of rat and bovine kidney. total nad+- and nadp+-dependent dehydrogenase activity was ... | 1975 | 2961 |
| ecological effect of control of african trypanosomiasis. | | 1976 | 2977 |
| studies on fragments of rod outer segments from bovine retinas. | monolayers of fragments of our rod segments were formed at an air-water interface. the area of these particles was measured as a function of the ph of the aqueous phase. a maximum area was measured at ph 6.5. the film was characterised by measuring the decrease in surface pressure, after compression, and the half time required to reach constant pressure. at a ph between 6 and 7 the decrease in surface pressure was a minimum. irradiation of films of fragments resulted in a decrease in surface pot ... | 1975 | 3051 |
| quantitative removal of carrier ampholytes from protein fractions derived from isoelectric focusing. | | 1975 | 3125 |
| acid phosphatase of hela cells: properties and regulation of lysosomal activity by serum. | | 1976 | 3137 |
| a reporter group delivery system with both absolute and selective specificity for thiol groups and an improved fluorescent probe containing the 7-nitrobenzo-2-oxa-1,3-diazole moiety. | 1. 4-(n-2-aminoethyl2'-pyridyl disulphide)-7-nitrobenzo-2-oxa-1,3-diazole (compound i) was synthesized and evaluated as a fluorescent labelling reagent for thiol groups. 2. the design of compound (i) as one example of a general type of reporter group delivery reagent (2-pyridyl-s-s-x, where x contains an environmentally sensitive spectroscopic probe) is discussed. 3. the electronic absorption spectrum of compound (i) was determined over a wide range of ph and the spectral changes that accompany ... | 1975 | 3168 |
| purification and properties of a low molecular weight protein factor of mitochondrial energy-linked functions. | 1. a soluble protein with a molecular weight of 11-12-10(3) has been isolated from bovine-heart mitochondria, which stimulates the following atp-dependent reactions of submitochondrial particles treated with 0.6 mm edta and 1 m nh4oh: reverse electron transfer from succinate to nad, transhydrogenation from nadh to nadp, and atp-pi exchange. the factor has no effect on the nadh oxidase, succinate oxidase and atpase activities of the particles. 2. the stimulatory effect of the factor in the atp-de ... | 1976 | 4097 |
| on the native structure of the histone h3-h4 complex. | | 1976 | 3176 |
| translational control of protein synthesis in stimulated wi-38 fibroblasts. | a cell-free protein synthesis system employing ribosomes from wi-38 human diploid fibroblasts was developed and its optimum mgc12 and kc1 levels and ph value found. the rate at which ribosomes are able to incorporate radioactive leucine into proteins (14cleucine incorporation/10 min/100 mug rrna) and the number of growing peptide chains 3hpuromycinpeptides formed/100 mug rrna) was determined. when confluent monolayers of wi-38 cells were stimulated to proliferate by serum, a transient increase i ... | 1976 | 3222 |
| comparison of four proteoglycans in terms of their interactions with poly(l-arginine). | | 1976 | 3231 |
| circular dichroism of collagen, gelatin, and poly(proline) ii in the vacuum ultraviolet. | | 1976 | 3232 |
| extraction of a calcium-phospholipid-phosphate complex from bone. | a calcium-phospholipid-phosphate complex with a constant 1:1 calcium to total phosphate molar ratio is shown to exist in rabbit and calf bone. this complex, which may be involved in the transport and deposition of bone mineral, appears to constitute a significantly greater proportion of the lipids of younger bone than of more mature bone. the comples was isolated by a modified folch extraction employing ultrasonic disruption of cellular material. evidence is presented to show that the complex is ... | 1976 | 3268 |
| an objective method for evaluating angus and hereford sperm motility. | angus and hereford sperm motility was evaluated by an objective spectrophotometric procedure and by a conventional subjective ranking system. semen was collected by electroejaculation and divided so that one group contained 6 angus samples and one group contained 12 hereford samples. objective procedures indicated that angus sperm was twice motile as hereford sperm in 2.9% sodium citrate. this objective procedure depends on the orientation of sperm in a flowing liquid and then spectrophotometric ... | 1975 | 3474 |
| fluorescence polarization studies on the binding between glutamate dehydrogenase and cytoplasmic aspartate aminotransferase. | polarization of fluorescence measurements on aspartate aminotransferase (from pig heart cytosol) labeled with fluorescein isothiocyanate have been used to detect the formation of a soluble complex of this protein wich glutamate dehydrogenase from bovine liver. the binding of the labeled transaminase to dehydrogenase is detectable at catalytic concentrations of the enzymes. | 1975 | 3487 |
| the disulfide bridges of the trypsin-kallikrein inhibitor k from snails (helix pomatia). thermal inactivation and proteolysis by thermolysin (author's transl). | isoinhibitor k is the main component of the complex mixture of isoinhibitors of broad specificity secreted into the mucus by the roman snail (helix pomatia). the disulfide pairing was determined after the amino acid sequence had been elucidated. two cystine-containing peptides with the disulfide bridges cys32-cys53 and cys32-cys53 plus cys7-cys57 were obtained after thermolytic hydrolysis of the native inhibitor at 80 degrees c and chromatographic separation of the peptides using se-sephadex. th ... | 1976 | 3462 |
| hydrogen exchange at the amide group of reduced pyridine nucleotides and the inhibition of that reaction by dehydrogenases. | stopped flow ultraviolet spectroscopy has been used to measure the rate of hydrogen exchange with solvent at the amide group of reduced nicotinamide nucleotide coenzymes. several mechanisms for the exchange reaction are considered in the light of the kinetic data. complex formation between the coenzyme and any of four dehydrogenases markedly slows the rate of hydrogen exchange. hydrogen bond formation and/or hydrophobic interactions within these complexes are thought to be the reasons for the de ... | 1976 | 3505 |
| inactivation of viruses in serum with binary ethyleneimine. | the inactivation os six strains from three different groups of viruses with 0.001 m binary ethyleneimine at 37 c proceeded at the same rate in either bovine serum or cell culture medium. the inactivant did not impair the growth-promoting capacity of bovine serum used in cell culture, nor did it affect the antibody activity of guinea pig hyperimmune serum. | 1976 | 3517 |
| guanylate cyclase in vertebrate retina:evidence for specific association with rod outer segments. | | 1976 | 3628 |
| binding study of tetracyclines to human serum albumin using difference spectrophotometry. | the binding of several tetracyclines to human serum albumin was studied using difference spectrophotometry and a spectrophotometric probe, 2-(4'-hydroxybenzeneazo)benzoic acid. difference spectra observed for the interaction between the probe and human serum albumin were similar to probe-bovine serum albumin spectra but were less intense for a given concentration of probe and did not reach saturation as quickly. difference spectra for the tetracyclines were dependent on the characteristics of th ... | 1976 | 3641 |
| transitory postnatal hemolysis of calf red cells by amino acids. | among the amino acids which can be solubilized to give a concentration of 300 mm at near physiological ph, histidine and proline caused a complete hemolysis of newborn calf but not of adult cow red cells within 20 to 30 minutes at 38 degrees c. while hydroxyproline, valine, and serine resulted in a partial lysis of calf cells, threonine, glutamine, and glycine were ineffective. in this communication, emphasis has been focused on the mode of the lytic process by histidine which was found to be af ... | 1976 | 3653 |
| purification and characterization of mouse interferon with novel affinity sorbents. | several novel selective sorbents for mouse interferon are described that exploit the hydrophobic property and glycoprotein nature of this molecule. low-molecular-weight ligands (hydrocarbons) and high-molecular-weight ligands (bovine serum albumin) immobilized on agarose bind selectively mouse l-cell interferon. the high selectivity of binding is due primarily to a hydrophobic effect, although electrostatic forces are also apparently involved. mouse l-cell interferon binds to immobilized serum a ... | 1976 | 3666 |
| tissue specific inhibition of lymphocyte proliferation by spleen extract (lymphocyte chalone) (author's transl). | aqueous spleen extracts were purified using acetone precipitation, membrane filtration, affinity chromatography, and dialysis. these extracts were able to inhibit thymidine incorporation into lymphoid cells (mkt-ch and pha-stimulated lymphocyte cultures). they did not influence non lymphoid tissue (melanoma cells mel ei 78 and ehrlich ascites cells). the inhibition was reversible and the purified extracts were not cytotoxic. the extracts correspond to a chalone. their importance for prevention o ... | 1976 | 3682 |
| conformational changes of hyaluronic acid in acid medium (author's transl). | both vitreous body homogenate and a fibrous product containing hyaluronic acid and collagen isolated from vitreous humor by acetone precipitation were investigated to elucidate the liquefaction of vitreous body by acids. graphic evaluation of the titration with hydrochlorid acid and viscosity measurements suggest a changed of the hyaluronic acid molecule in the ph-range between 5.2 and 4.1. between these ph-values the ionization of carboxyl groups is decreased accompanied by conformational chang ... | 1976 | 3986 |
| scanning electron microscopic study of chylomicrons incubated with lipoprotein lipase. | the effects of lipolysis on the structure of chylomicrons were studied with the scanning electron microscope using rat chylomicrons incubated with purified bovine milk lipoprotein lipase for 20 minutes at ph 8.1. since the amount of albumin added to the medium was limited, some of the free fatty acids and partial glycerides formed by lipolysis accumulated in the chylomicrons. lipolyzed chylomicrons fixed with oso4 at ph 7.4 appeared in scanning electron micrographs as spheres with multiply ident ... | 1976 | 3992 |
| identification of immunoglobulins associated with complement fixation, agglutination, and low ph buffered antigen tests for brucellosis. | serums from infected cattle, cattle with persistent postvaccinal antibody, and serologically "positive" noninfected cattle were fractionated into major immunoglobulin classes by diethylaminoethyl (deae)-cellulose chromatography and by sucrose density gradient centrifugation. each fraction was assayed for anti-brucella activity by standard tube-agglutination test (stt), buffered tube-agglutination test (btt), and complement-fixation test (cf). in the serums from experimentally infected cattle, an ... | 1976 | 3997 |
| on the mechanism of action of alkylguanidines in oxidative phosphorylation: their action on soluble f1. | | 1976 | 4031 |
| activity of imidazole on the hydrolysis of cyclic amp and cyclic gmp by bovine heart and rat liver cyclic nucleotide phosphodiesterases. | | 1976 | 4034 |
| nuclear magnetic resonance titration curves of histidine ring protons. ribonuclease s-peptide and s-proteins. | the histidine c-2 proton nmr titration curves of ribonuclease s-peptide (residues 1 to 20) and s-protein (residues 21 to 124) are reported. although s-protein contains 3 histidine residues, four discrete resonances are observed to titrate. one of these arises from the equivalent histidine residues of unfolded s-protein. the variation in area of the four resonances indicate that there is a reversible ph-dependent equilibrium between the folded and unfolded forms of s-protein, with some unfolded m ... | 1976 | 4455 |
| enzymic hydrolysis of acetylcarnitine in liver from rats, sheep and cows. | 1. the enzymic utilization of o-acetyl-l-carnitine other than via carnitine acetyltransferase (ec 2.3.1.7) was investigated in liver homogenates from rats, sheep and dry cows. 2. an enzymic utilization of o-acetyl-l-carnitine via hydrolysis of the ester bond to yield stoicheiometric quantities of acetate and l-carnitine was demonstrated; 0.55, 0.53 and 0.30mumol of acetyl-l-carnitine were utilized/min per g fresh wt. of liver homogenates from rats, sheep and dry cows respectively. 3. the acetylc ... | 1975 | 4059 |
| the action of tributyltin on energy coupling in coupling-factor-deficient submitochondrial particles. | 1. tributyltin at concentrations of approx. 1nmol/mg of protein induces respiratory control and lessens the protein permeability of coupling-factor-deficient submitochondrial particles. 2. at these concentrations or lower, it increases the p/o ratio of the particles to a small extent and inhibits the adenosine triphosphatase activity without greatly increasing its sensitivity to uncoupling agents. 3. it fails to stimulate atp-driven reversed electron transport or transhydrogenase, but stimulates ... | 1975 | 4063 |
| construction of mitochondrial h+ -transporting system in proteoliposomes. | | 1976 | 4070 |
| bovine pancreatic lipase.i.isolation, homogeneity, and characterization. | bovine pancreatic lipase was isolated in pure form by lyophilization of fresh bovine pancreas, extraction of the enzyme with sucrose solution, fractional precipitation with ammonium sulfate and acetone, followed by chromatography on sephadex g-100. the specific activity of the purest lipase fraction was 1750 micromoles fatty acid, liberated in 30 min per milligram of protein, indicating a purification of approximately 473-fold, with an overall yield of about 42%. homogeneity of the enzyme was co ... | 1976 | 4478 |
| distribution and removal of cadmium from milk. | distribution of added cadmium in milk systems and the feasibility of removing cadmium were investigated. in milk containing 1 ppm cadmium, 96% of the added cadmium chloride was dispersed in the skim milk fraction, and 3% was associated with the cream fraction. cadmium was not bound strongly to any protein fraction. the association of cadmium with acid casein, whey proteins, and the fat globule membrane was 18,6, and .5% of total added cadmium. with a 5-min exposure thiosuccinylated amino-ethyl c ... | 1976 | 4479 |
| interaction of benzodiazepine derivatives with bovine serum albumin-ii. circular dichroism studies. | | 1976 | 4074 |
| equilbrium and kinetics of the unfolding of alpha-lactalbumin by guanidine hydrochloride (ii). | the reversible unfolding of alpha-lactalbumin by guanidine hydrochloride, was studied at 25.0 degrees c in a relatively low concentration range of the denaturant (0.80-2.00 mol/l) by means of difference spectra and ph-jump measurements. the unfolding was shown to occur between two states, n and d, because apparent rate-constants of the unfolding and the refolding reactions depended only on ph. all curves plotted as the logarithmical equilibrium constant log kd against ph could fall on the same b ... | 1976 | 4110 |
| characterization of protein kinases from bovine parotid glands. the effect of tolbutamide and its derivative on these partially purified enzymes. | 1. four fractions of protein kinase (ec 2.7.1.37) activity (peak ih, iih, iiic and ivc) have been resolved and partially purified from the 100 000 x g supernatant fraction of bovine parotid glands by deae-cellulose and phosphocellulose chromatographies. 2. the protein kinases of peak ih and iih were adenosine 3',5'-monophosphate (cyclic amp) -dependent and had similar enzymic properties. the enzyme activities of peak iiic and ivc were cyclic-amp independent, but there were some distinct differen ... | 1976 | 4116 |
| a study of the single polypeptide nature of rhodanese. a comparison of different preparations. | the enzyme rhodanese (ec 2.8.1.1) appears as a single polypeptide chain protein on sodium dodecyl sulfate-polyacrylamide gel electrophoresis. the molecular weight of this species is approx. 33 000. this contrasts with previous reports that rhodanese behaves on gel filtration chromatography as a rapidly equilibrating monomer-dimer system composed of identical subunits with a molecular weight of 18 500. we have investigated this apparent discrepancy by isolating the enzyme by the two different pre ... | 1976 | 4117 |
| cow's milk alkaline phospharase. ii. subunit structure, metalloproteic nature and kinetic parameters (author's transl). | alkaline phosphatase (ec 3.1.3.1) from cow's milk as a dimer comprising two identical or very similar subunits of about 85 000 molecular weight. the enzyme contains 4.9 +/- 0.6 gatoms of zinc per mol of protein. the essential kinetic properties are the same as those of other alkaline phosphatases: variation of ph optimum value, the lack of specificity, increase of km and v with ph value. the phosphotransferase activity is enlarged, at constant concentration of acceptor, with an increasing concen ... | 1976 | 4119 |
| separation of two pz-peptidases from bovine dental follicle. | two pz-peptidases (ec 3.4.-) (a and b) cleaving a synthetic substrate for collagenase, 4-phenylazobenzyloxycarbonyl-l-pro-l-leu-gly-l-pro-d-arg (pz-peptide) have been separated from the particulate fraction of bovine dental follicle. pz-peptidase a had a molecular weight of 220 000, an optimum ph at 8.0-8.5, and a km value of 67 mum toward pz-peptide at ph 7.1, whereas pz-peptidase b had a molecular weight of 20 000, an optimum ph at 6.5-6.7, and a km value of 400 mum toward pz-peptide at ph 7.1 ... | 1976 | 4136 |
| the effect of formate on cytochrome aa3 and on electron transport in the intact respiratory chain. | 1. formate inhibits cytochrome c oxidase activity both in intact mitochondria and submitochondrial particles, and in isolated cytochrome aa3. the inhibition increases with decreasing ph, indicating that hcooh may be the inhibitory species. 2. formate induces a blue shift in the absorption spectrum of oxidized cytochrome aa3 (a3 + a33+) and in the half-reduced species (a2 + a33+). comparison with cyanide-induced spectral shifts, towards the red, indicates that formate and cyanide have opposite ef ... | 1976 | 4141 |
| acetylcholinesterase. ii. experimental aspects of interaction with reversible effectors under conditions of high ionic strength. | interaction of usual effectors with acetylcholinesterase (ec 3.1.1.7) from bovine erythrocytes was examined under conditions of high ionic strength (gamma/2 greater than or equal to 0,1). detailed kinetic investigation of the hydrolysis of acetylcholine by acetylcholinesterase in the presence of modifiers shows that the effects produced by numerous quaternary nitrogen compounds on the enzyme can be explained on the basis of binding of the effectors to the anionic subsite of the active center. th ... | 1975 | 4154 |
| endonuclease activity in bull semen, testis and accessory sex organs. | | 1975 | 4164 |
| resolution, specificity and transphosphorylase activity of calcifying cartilage alkaline phosphatases. | the phosphate releasing activity from calf scapula cartilage was resolved by deae-cellulose chromatography into two distinct phosphatase activities. the activity eluted first from the column (phosphatase i) was active towards a variety of phosphate esters and several linear oligo phosphates including sodium pyrophosphate, while the second phosphatase activity (phosphatase ii) was active only towards simple phosphate esters. phosphatase i acted towards oligo phosphates in a stepwise fashion hydro ... | 1976 | 4199 |
| studies related to antitumor antibiotics. part v. reactions of mitomycin c with dna examined by ethidium fluorescence assay. | the cytotoxic action of the antitumor antibiotic mitomycin c occurs primarily at the level of dna. using highly sensitive fluorescence assays which depend on the enhancement of ethidium fluorescence only when it intercalates duplex regions of dna, three aspects of mitomycin c action on dna have been studied: (a) cross-linking events, (b) alkylation without necessarily cross-linking, and (c) strand breakage. cross-linking of dna is determined by the return of fluorescence after a heat denaturatio ... | 1976 | 4201 |
| studies on the formation by rat brain preparations of cdp-diglyceride from ctp and phosphatidic acids of varying fatty acid compositions. | the enzyme, ctp:phosphatidate cytidylyltransferase (ec2.7.7.41) which catalyses formation of cdp-diglyceride from ctp and phosphatidic acid has been studied in rat brain preparations and other tissues. improvement, as judged by the higher tissue activities obtained, in the assay method for this enzyme was achieved through use of phosphatidic acids sonicated in buffer-detergent solution saturated with ether and containing bovine serum albumin and use of short incubation times which essentially pr ... | 1976 | 4204 |
| distribution of releasing factors, biogenic amines, and related enzymes in the bovine median eminence. | the bovine median eminence was dissected into eight different subdivisions: rostral, anterior internal, anterior external, middle external medial, middle external lateral, middle internal medial, middle internal lateral, and caudal. thyrotropin-releasing hormone (trh) was found in the highest concentrations in the middle external medial and lateral subdivisions; luteinizing hormone-releasing hormone (lhrh) was concentrated in the middle external lateral and anterior internal subdivisions. among ... | 1976 | 4296 |
| conformational studies of two non-histone chromosomal proteins and their interactions with dna. | the conformational properties of two non-histone chromosomal proteins (high-mobility-group proteins 1 and 2) have been studied by spectroscopic methods. the interaction of high-mobility-group protein 1 with dna has also been studied. 1. circular dichroism results indicate that in the presence of salt both proteins are 40-50% helical between ph 1 and 9. above ph 9 denaturation takes place. in the absence of salt the proteins denature below ph 4. 2. nuclear magnetic resonance spectra show the pres ... | 1976 | 4304 |
| pre-existence of the active site in zymogens, the interaction of trypsinogen with the basic pancreatic trypsin inhibitor (kunitz). | | 1976 | 4338 |
| studies on bovine rumen bacterial urease. | | 1976 | 4420 |
| guanylate cyclase and cyclic guanosine 3':5'-monophosphate phosphodiesterase activities and cyclic guanosine 3':5'-monophosphate levels in normal and transformed fibroblasts in culture. | to investigate the role of guanosine 3':5'-monophosphate (cyclic gmp) in cultured cells we have measured guanylate cyclase and cyclic gmp phosphodiesterase activities and cyclic gmp levels in normal and transformed fibroblastic cells. guanylate cyclase activity is found almost exclusively in the particulate fraction of normal rat kidney (nrk) and balb 3t3 cells. enzyme activity is stimulated 3- to 10-fold by treatment with the detergent lubrol px. however, enhancement of guanylate cyclase by fib ... | 1976 | 4444 |
| reconstitution and characterization of the adenine nucleotide transporter derived from bovine heart mitochondria. | 1. adenine nucleotide exchange-transport was reconstituted in vesicles prepared from phospholipids and protein fractions derived from bovine heart submitochondrial particles. the transport, which was specific for atp and adp was measured either as adp/adp, atp/atp, or adp/atp exchange. the highest specific activity (370 nanomoles of adp/adp exchange/min/mg of protein at room temperature) was obtained with a protein fraction prepared by cholate extraction of partly resolved submitochondrial parti ... | 1976 | 4448 |
| nuclear magnetic resonance titration curves of histidine ring protons. a direct assignment of the resonances of the active site histidine residues of ribonuclease. | one of the four titrating histidine ring c-2 proton resonances of bovine pancreatic ribonuclease has been assigned to histidine residue 12. this was accomplished by a direct comparison of the rate of tritium incorporation into position c-2 of histidine 12 of s-peptide (residues 1 to 20) derived from ribonuclease s, with the rates of deuterium exchange of the four histidine c-2 proton resonances of ribonuclease s under the same experimental conditions. the same assignment was obtained by a compar ... | 1976 | 4454 |
| age related variations in plasma electrolytes of hereford cattle under range conditions. | | 1976 | 5228 |
| physical and kinetic properties of homogenous bovine lens aldose reductase. | aldose reductase from calf lens was purified 15,000-fold. the homogeneity of the final preparation was demonstrated by molecular sieve chromatography, analytical ultracentrifugation, sodium dodecyl sulfate gel electrophoresis, ouchterlony immunodiffusion, and polyacrylamide gel electrophoresis at three ph values. the monomeric nature of the enzyme is suggested by the molecular weight of 37,000 from both molecular sieve chromatography and sodium dodecyl sulfate-gel electrophoresis with beta-merca ... | 1976 | 4458 |
| dephosphorylation of bovine casein by milk alkaline phosphatase. | the ph of optimum activity of alkaline phosphatase from cow's milk depended on the substrate, being 10-1 for rho-nitrophenylphosphate, 8-6 for phosphoserine, 8-0 for phosvitin and 6-8 for casein. individual casein components were dephosphorylated more rapidly than mixtures of alphas- and beta-caseins or of alphas-, beta-and kappa-caseins and micellar casein. mixtures of 2 components involving kappa-casein were more readily dephosphorylated than alphas- and beta-casein mixtures. at ph 6-8, lactos ... | 1976 | 4476 |
| a kinetic concepto of lipid transport in ruminants. | summarization of the literature shows a strong correlation between dietary fatty acid intake and total lipid concentration in plasma in lactating cows whereas total milk fat secreted is related to neither of these. in the process of plasma triglyceride removal, chylomicra and very low density lipoproteins are converted to low density lipoproteins. limited kinetic data indicate that the fractional removal rates for chulomicra and very low density lipoproteins are rapid in lactating cows whereas f ... | 1976 | 4477 |
| the biological actions of thyrotropin. | | 1975 | 4827 |
| 5-aminolaevulinic acid dehydratase: structure, function, and mechanism. | delta-aminolaevulinic acid dehydratase catalyses the synthesis of porphobilinogen. the enzyme has a molecular mass of 285000 and is composed of eight similar subunits of molecular mass 35000. the n-terminal amino acid is acylated, and the number of peptides found on tryptic digestion equals the number of lysine and arginine residues per mass of 35000. the eight subunits are apparently arranged at the corners of a cube and therefore have dihedral (d4) symmetry. the bovine liver enzyme which has b ... | 1976 | 4832 |
| study of cystinaminopeptidase heterogeneity in animal sera by the isoelectric focusing method. | study of the quantitative distribution of cystinaminopeptidase activity in the serum of pregnant and control animals (cow, sheep and rat) by the isoelectric focusing method showed heterogeneity of the cystinaminopeptidase activity of the animals' serum enzymatic system, which was well pronounced in the cow and rat and less pronounced in the sheep. the authors assume from their results that the principal difference between the pregnant and control animals is not the total increase in the level of ... | 1976 | 4848 |
| inhibition of prostaglandin biosynthesis by sulphasalazine and its metabolites. | sulphasalazine (sz) inhibits prostaglandin (pg) biosynthesis in vitro with a potency comparable to that of aceylsalicylate. the metabolites of sz, sulphapyridine and 5-aminosalicylic acid, were of considerably lower potency as inhibitors of pg biosynthesis in the synthetase preparations used. th inhibition of prostaglandin production by sz could at least partly account for the clinical utility of sulphasalazine in ulcerative colitis. sulphapyridine may help to maintain inhibitory concentrations ... | 1976 | 4854 |
| activation of tyrosine hydroxylase by polyanions and salts. an electrostatic effect. | the activity of a partially purified preparation of tyrosine hydroxylase (ec 1.14.16.2) from the bovine caudate nucleus was increased by heparin, chondroitin sulfate, phosphatidylserine, polyacrylic acid, polyvinyl sulfuric acid and both poly-d-, and poly-l-glutamic acids, all polyanions. a variety of salts both activated the enzyme and prevented the activation by the polyanions. the observations that activity is increased when the enzyme interacts with salts and with macromolecules of high nega ... | 1976 | 4122 |
| removal of phosphate groups from casein with potato acid phosphatase. | potato acid phosphatase (ec 3.1.3.2) was used to remove the eight phosphate groups from alphas1-casein. unlike most acid phosphatases, which are active at ph 6.0 or below, potato acid phosphatase can catalyze the dephosphorylation of alphas1-casein at ph 7.0. although phosphate inhibition is considerable (k1=0.42 mm phosphate), the phosphate ions produced by the dephosphorylation of casein can be removed by dialysis, allowing the reaction to go to completion. the dephosphorylated alphas1-casein ... | 1976 | 4132 |
| hormones, second messengers, and the mammalian spermatozoon. | | 1975 | 4967 |
| the rotating aeration system fuchs system in the treatment of liquid animal and municipal wastes. 3. hygienic studies on the rotation aeration of cattle slurry. | | 1976 | 5074 |
| energy coupling in lysolecithin-treated submitochondrial particles. | | 1976 | 5087 |
| physical studies of the nonhistone chromosomal proteins hmg-u and hmg-2. | the nonhistone chromosomal proteins, hmg-1 and hmg-2, have a folded conformation, with a high alpha-helical content, over a wide ph range. at high and low ph values, the molecules unfold. both molecules contain cysteine and tryptophan. the tryptophans appear to be buried in the folded form. hmg-1 shows aggregation at ph 5.7, as does hmg-2 at ph 9.0. the folded form is insensitive to high concentrations of salt, suggesting that charge-charge interaction plays no role in stabilizing the tertiary s ... | 1976 | 5107 |
| laser raman spectroscopic studies of the thermal unfolding of ribonuclease a. | the reversible thermal denaturation of bovine pancreatic ribonuclease a at ph 5 in 0.1 m nacl over the range 32-70 degrees c as studied by raman spectroscopy proceeds in a gradual manner consistent with a stepwise unfolding process rather than as a transition between two states. conversion of residues from helical or pleated-sheet geometry to some intermediate geometry, as followed by means of the amide i and iii lines, reveals that substantial amounts of the helical and pleated-sheet conformati ... | 1976 | 5118 |
| spectroscopic studies on the complex formation of suramin with bovine and human serum albumin. | the binding of suramin to bovine and human serum albumin was investigated by gel filtration and spectroscopic measurements. besides some low-affinity binding sites suramin has, on the bovine serum albumin molecule one and on the human serum albumin molecule two, high-affinity binding sites. spectroscopic measurements reveal that there are large differences between the albumins in the mechanism of binding to the high-affinity binding sites. further, it is suggested that high concentrations of sur ... | 1976 | 5125 |
| oxidation of n-methyl substituted hypoxanthines, xanthines, purine-6,8-diones and the corresponding 6-thioxo derivatives by bovine milk xanthine oxidase. | 1. the oxidation of six series of purines (hypoxanthines, xanthines, purine-6,8-diones and the corresponding 6-thioxo derivatives) by a highly purified bovine milk xanthine oxidase (ec 1.2.3.2) has been studied, using a variety of n-methyl derivatives. 2. n-methyl substituents can either enhance or reduce enzymic rates. enhancement is ascribed to blockade of groups which mediate unfavorable modes of binding of substrate to enzyme. introduction of n-methyl groups can also inhibit enzymic oxidatio ... | 1976 | 5139 |
| multiple forms of histone acetyltransferases in the cytosol of calf endometrium. | the histone acetyltransferase (ec 2.3.1.-) activity of calf endometrium cytosol has been separated into three separate activities by stepwise chromatography on deae-cellulose. in addition to differential elution from the deae-cellulose, the three activities are differentiated by their ph optima, preferences for histone subfractions as substrates, and stability to heat denaturation. peak i has an optimum of ph 8.7 and preferentially acetylates histones f2b and f3; peak ii has an optimum of ph 8.5 ... | 1976 | 5140 |
| steady-state enzyme kinetics of the pancreatic ribonucleases from five mannalian species. | the kinetic parameters km, k+2 and k+2/km of the pancreatic ribonucleases (ec 3.1.4.22) from cow, giraffe, horse, rat and lesser rorqual have been determined, using 2',3'-cyclic cytidine monophosphate and 2',3'-cuclic uridine monophosphate as substrates. no large differences were found between the activities of the five enzymes. the relative differences between the activities of the five enzymes are mainly due to differences in the rates of hydrolysis and not to differences in the affinities for ... | 1976 | 5144 |
| the effect of soluble rat liver proteins on the activity of microsomal stearoyl-coa and linoleoyl-coa desaturase. | 1. the influence of bovine serum albumin and soluble rat liver proteins on the activity of rat liver microsomal delta9 and delta6 desaturases has been studied. 2. in the absence of bovine serum albumin, the delta9 desaturase which converts stearoyl-coa into oleoyl-coa, shows a non-linear correlation between enzyme activity and protein concentration. 3. optimum concentrations of bovine serum albumin have three main effects on the enzyme activity: (i) establishes a linear relationship between enzy ... | 1976 | 5153 |
| study of the natural antihistamine-like substance in bile in mammals. | a natural antihistamine substance (nas) present in bile has been investigated. it was found that the antihistamine activity was not due to proteins, lipids, pigments, or amino acids. on ion exchange chromatography and thin-layer chromatography, this activity was associated with bile acids. many bile acids could, in varying degrees, inhibit this histamine induced guinea pig ileum contraction, desoxycholic acid being the most potent. however nas activity could be separated from bile acids and thei ... | 1976 | 5181 |
| xylanase (hemicellulase) activity in cell-free rumen fluid. | it has been shown that there is hemicellulase (xylanase) activity in cell-free filtrates of rumen liquor. this activity changes during the feeding cycle. the optimal ph and temperature for this activity have been found, as have the substrate-to-enzyme ratios. many reagents, particularly heavy metal ions and phenols, inhibit the activity, but the activity is enhanced by reducing agents. no activity towards monosaccharides, disaccharides, or glycosides was found. the xylanase component was not sta ... | 1976 | 5191 |
| photooxidation of bovine neurophysin ii in the presence of rose bengal. | | 1976 | 5196 |
| differential dependence on nadph concentrations of two microsomal corticosteroid 21-hydroxylation reactions. | the dependency on nadph concentrations of the bovine adrenal cortex microsomal 21-hydroxylation of progesterone and of 17-hydroxyprogesterone was investigated. the average km for nadph in the 21-hydroxylation of progesterone is 10.4 mum while that for the 21-hydroxylation of 17-hydroxyprogesterone is 0.6 mum. the optimal nadph concentrations for these two hydroxylations are, in average, one order of magnitude apart. the different affinities of the two 21-hydroxylating activities with respect to ... | 1976 | 5267 |
| equilibrium protection studies of the interaction of bovine glutamate dehydrogenase with purine nucleotide effectors. | | 1975 | 5298 |
| monovalent cation penetration into synaptic membranes. | | 1975 | 5301 |
| isolation of mitochondrial dna, purified of nuclear dna, from animal tissues (degree of methylation and level of pyrimidine nucleotide clustering--criteria of purity). | a method of preparation of mitochondria free of nuclear dna and its fragments by treatment of mitochondria with deae-cellulose has been developed. this method is based on binding nuclear nucleic acids and nucleoproteins to deae-cellulose particles in the media used for isolation of mitochondria. treatment with deae-cellulose under the conditions described does not induce any visible degradation of mitochondria and mitochondrial dna. the mitochondrial dna preparations obtained from beef and rat l ... | 1976 | 6074 |
| reversible uncoupling of the copper and cobalt spin systems in cobalt bovine superoxide dismutase at low ph. | | 1975 | 5307 |
| the interrelationship between the inhibitory activity of milk with different types of beta-lactoglobulins and the resistance of cattle to mastitis. | in the course of the investigation of piebald (black-white) cattle it is found that 17,62% animals produce the aa type beta-lactoglobulin, 49,52%--the ab type and 32,86%--the bb type. the higher inhibitory activity of milk with the bb type beta-lactoglobulin was found which retained in dilution 1 : 32. the total flora of teat, cyst and parenchyma milk of animals with the bb type beta-lactoglobulin as well as enterococcus bacteria were much lower than in milk of cows with the aa type homogenous f ... | 1975 | 5340 |
| nonspecific bactericidal activity of the lactoperoxidases-thiocyanate-hydrogen peroxide system of milk against escherichia coli and some gram-negative pathogens. | two strains of escherichia coli and one strain each of salmonella typhimurium and pseudomonas aeruginosa were killed by the bactericidal activity of the lactoperoxidase-thiocyanate-hydrogen peroxide system in milk and in a synthetic medium. h2o2 was supplied exogenously by glucose oxidase, and glucose was produced at a level which was itself noninhibitory. two phases were distinguished: the first phase was dependent on the oxidation of scn(-) by lactoperoxidase and h2o2, which was reversed by re ... | 1976 | 5374 |
| studies on d-tetrose metabolism. vi. crystallization and some properties of d-erythrulose reducatase from beef liver. | d-erythrulose reductase of beef liver was crystallized from ammonium sulfate solution at ph 8.17. the crystals are needle-shaped. the enzyme protein contains 851 amino acid residues per mole of the enzyme: lys28, his11, arg52, asp79, thr58, ser56, glu68, pro20, gly80, ala107, val112, met24, ile31, leu88, tyr7, phe22, trp4, and cys4. the enzyme is inactivated by exposure to temperatures below 12degrees. the inactivation is accelerated by increasing the salt concentration and decreasing the enzyme ... | 1975 | 5410 |