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laser light scattering bioassay for 1-beta-d-arabinofuranosylcytosine (ara-c, nsc-63878).a bioassay method for the estimation of ara-c in biological samples which utilizes laser light scattering from suspensions of drug-sensitive bacteria has been developed. the species employed in the assay was streptococcus faecium var. durans resistant to methotrexate and 6-mercaptopurine. in less than four hours, serum and urine levels of ara-c can be reproducibly measured using the method. a sample volume of 0.1 ml containing 30 ng/ml may be assayed with a precision of +/-10 percent. the presen ...1978674821
the effect of compounds which degrade hydrogen peroxide on the enumeration of heat-stressed cells of salmonella senftenberg.greater than 90% of heat-stressed cells of salmonella senftenberg failed to grow on trypticase soy agar. adding to this medium compounds which are capable of degrading hydrogen peroxide allowed growth of the heat-injured cells. these compounds did not stimulate growth of heated cells of streptococcus faecium, an organism which does not possess catalase.1978679073
inhibition of peptidoglycan biosynthesis at a postcytoplasmic reaction in a stable l-phase variant of streptococcus faecium.cultures of a stable l-phase variant of streptococcus faecium f24 produced and retained peptidoglycan precursors intracellularly over the entire growth cycle in a chemically defined medium. the identity of the most abundant precursor, udp n-acetylmuramyl-l-alanyl-d-glutamyl-l-lysyl-d-alanyl-d-alanine (udp-murnac-pentapeptide), was confirmed by demonstrating in vitro the presence of enzymes required for the cytoplasmic stage of peptidoglycan biosynthesis. the initial membrane-bound reaction in pe ...1978690080
synthesis and biological activities of some uronic acids, uronates, uronamides, and urononitriles of pyrimidine nucleosides.the 5'-hydroxymethylene function of several uracil and cytosine nucleosides has been modified to produce a variety of uronic acids, uronates, uronamides, and urononitriles of 2'-deoxy-beta-d-erythro-pentofuranosyl- and beta-d-arabino-pentofuranosylpyrimidines. in addition, the 5 position in many of these nucleosides has been substituted by a halogen atom. twenty-one of the 35 compounds synthesized and examined for biological activity have not been previously reported. the purity of the products ...1978214555
semiautomated turbidimetric microbiological assay for cefazaflur.a quantitative semi-automated turbidimetric bioassay for cefazaflur, using streptococcus faecium as the indicator, is described. assays were run at ph 6.5 approximately 7 for 3.75 hours at 37 degrees c using 2 approximately 12 microgram cefazaflur per ml assay broth for standards. the dose response line was plotted point to point using the natural log of the absorbance vs natural log of the concentration. this assay is both accurate and precise and is more rapid than traditional plate assays for ...197826651
carriage of group d streptococci in the human bowel.sixty faecal samples, 39 from adults and 21 from neonates, were investigated by means of a simple scheme to isolate and identify any group d streptococci present. a number of differences were found between the two groups. group d streptococci were absent from 43% of the neonates compared with only 13% of the adults; streptococcus bovis was commoner in the neonates (23.8%) than in the adults (5%), and streptococcus faecium was not isolated from any of the infant samples although it was common in ...1978107199
cellular autolytic activity in synchronized populations of streptococcus faecium.the autolytic capacity of streptococcus faecium (s. faecalis atcc 9790) varied during synchronous cell division. this phenomenon was initially observed in rapidly dividing populations (td=30 to 33 min) synchronized by a combination of induction and size selection techniques. to minimize the problems inherent in studies of cells containing overlapping chromosome cycles and possible artifacts generated by induction techniques, the autolytic capacities of slowly dividing populations (td=60 to 110 m ...1978415050
incidence and relationship of group d streptococci with other indicator organisms in meats.raw and processed meats were analyzed for presumptive group d streptococci using kf streptococcus agar. counts were compared with coliform, presumptive escherichia coli, and enterobacteriaceae counts but no meaningful relationships were observed. results indicated that group d streptococci and e. coli type i were principally contaminants from the packing plant, rather than at retail level. the predominating group d streptococcus in both beef and pork cuts was streptococcus faecalis, while in pro ...1978106944
characterization of plasmids in bacteriocin producing strains of streptococcus faecium.four bacteriocin (enterocin) producing strains of streptococcus faecium were examined for extrachromosomal dna. three strains proved to harbor minicircular plasmid dna of uniform length as evidenced by cscl ethidium bromide density centrifugation and electron microscopy. molecular weight determination obtained through contour length measurements showed 2.4 x 10(6) dalton for s. faecium 25, 3.4 x 10(6) dalton for s. faecium 3 and 3.8 x 10(6) dalton for s. faecium 59. elimination experiments for b ...1978104480
[the etiology of foul brood].five hundred and thirty-six samples of honeycombs were examined in a laboratory in the years 1971-1974. in all the samples clinically determined as the foul brood, b. alvei was isolated as a pure culture, and enterococci, or both microorganisms were isolated in mixed form. twenty-five strains of the isolated streptococci were analyzed microbiologically and biochemically; on the basis of their culture and biochemical characteristics five strains were designated as streptococcus faecalis, 14 strai ...1978102071
dihydrofolate reductase from amethopterin-resistant lactobacillus casei. sequences of the cyanogen bromide peptides and complete sequences of the enzyme.the complete amino acid sequence of dihydrofolate reductase from an amethopterin-resistant strain of lactobacillus casei has been determined by sequence analysis of peptides produced by cleavage with cyanogen bromide, trypsin, staphylococcal protease, and myxobacter protease. comparison of this sequence with those of reductases from other bacterial sources shows that the enzymes are homologous. the lactobacillus casei reductase sequences shows a 29% sequence identity with that of the escherichia ...197898527
approximation of the cell cycle in synchronized populations of streptococcus faecium.slowly growing populations (td = 70 to 80 min) of streptococcus faecium (s. faecalis atcc 9790) were synchronized by selection after sucrose gradient fractionation. the cell cycle was approximated by correlating the patterns of dna accumulation and cell division. more specifically, the beginning of cell cycle was equated with the beginning of a rapid linear increase in dna accumulation. the dna content of the culture approximately doubled during the period of accumulation, which lasted about 51 ...197896099
relationship between cellular autolytic activity, peptidoglycan synthesis, septation, and the cell cycle in synchronized populations of streptococcus faecium.synchronized, slowly growing (td = 70 to 80 min) cultures were used to study several wall-associated parameters during the cell cycle: rate of peptidoglycan synthesis, septation, and cellular autolytic activity. the rate of peptidoglycan synthesis per cell declined during most of the period of chromosome replication (c), but increased during the latter part of c and into the period between chromosome termination and cell division (d). an increase in cellular septation was correlated with the inc ...197896095
purification and properties of l-alpha-glycerophosphate oxidase from streptococcus faecium atcc 12755.a procedure was developed to purify the streptococcus faecium atcc 12755 l-alpha-glycerophosphate oxidase. the molecular weight of the purified enzyme was 131,000 and the subunit molecular weight was 72,000. two moles of fad were bound/mol of enzyme. apo-l-alpha-glycerophosphate oxidase displayed physical properties similar to the holoenzyme as judged by electrophoresis in 10% buffer gels at ph 8.5 and by centrifugation in a 5 to 20% linear sucrose gradient. the apoenzyme was completely reactiva ...1979429313
methotrexate, a high-affinity pseudosubstrate of dihydrofolate reductase.investigations have been made of the slow, tight-binding inhibition by methotrexate of the reaction catalyzed by dihydrofolate reductase from streptococcus faecium a. quantitative analysis has shown that progress curve data are in accord with a mechanism that involves the rapid formation of an enzyme-nadph-methotrexate complex that subsequently undergoes a relatively slow, reversible isomerization reaction. from the ki value for the dissociation of methotrexate from the e-nadph-methotrexate comp ...197936135
folate analogues altered in the c9-n10 bridge region: 11-thiohomofolic acid.the synthesis of 11-thiohomofolic acid (2) has been accomplished by an unambiguous procedure. reaction of 1-chloro-4-[p-(carbomethoxy)thiophenoxy]-2-butanone (10) with hydroxylamine under carefully controlled conditions gave the corresponding oxime 33. conversion of this oxime to 1-phthalimido-4-[p-(carbomethoxy)thiophenoxy]-2-butanone oxime (4) was carried out by its reaction with potassium phthalimide using crown 18 ether as a catalyst. hydrazinolysis of compound 4 gave 1-amino-4-[p-(carbometh ...1979109615
enzymatic deacylation of lipoteichoic acid by protoplasts of streptococcus faecium (streptococcus faecalis atcc 9790).high-molecular-weight, micellar lipoteichoic acid (lta) was converted to a lower-molecular-weight, apparently deacylated polymer when the former was incubated in the presence of growing protoplasts of streptococcus faecium (s. faecalis atcc 9790), but not when incubated in fresh or spent protoplast medium. the mobility of the low-molecular-weight polymer upon agarose gel electrophoresis was indistinguishable from that of native extracellular lipoteichoic acid lta(x) from this organism or from ch ...1979108241
morphological and physiological study of autolytic-defective streptococcus faecium strains.three autolytic-defective mutants of streptococcus faecium (s. faecalis atcc 9790) were isolated. all three autolytic-defective mutants exhibited the following properties relative to the parental strain: (i) slower growth rates, especially in chemically defined medium; (ii) decreased rates of cellular autolysis and increased survival after exposure to antibiotics which block cell wall biosynthesis; (iii) decreased rates of cellular autolysis when treated with detergents, suspended in autolysis b ...1979108262
precursor-product relationship of intracellular and extracellular lipoteichoic acids of streptococcus faecium.exponential biosynthesis and excretion of lipoteichoic acid (lta) during the exponential phase of growth, and continued synthesis and excretion during valine starvation of streptococcus faecium (s. faecalis atcc 9790), were shown. during exponential growth, extracellular lta (ltax) accounted for approximately 13% of the total lta in cultures, whereas during valine starvation, this percentage increased to approximately 60% within 4 h. ltax was present in a low-molecular-weight, apparently deacyla ...1979106043
effect of growth rate on lipid and lipoteichoic acid composition in streptococcus faecium.the lipid composition of streptococcus faecium (s. faecalis atcc 9790) was analyzed at various growth rates. diphosphatidylglycerol and the non-ionic lipid fraction containing diacylglycerols and neutral glycolipids appeared to accumulate relative to cellular mass as the culture mass doubling time increased from 30 to 80 min. within the same range of doubling times the non-ionic lipid fraction appeared to become substantially enriched with diacylglycerols. all lipid species and cellular lipoteic ...1979116686
species-specific resistance to antimocrobial synergism in streptococcus faecium and streptococcus faecalis.combinations of penicillin with various aminoglycosidic aminocyclitols were tested against a collection of clinical isolates of streptococcus faecium in vitro and were used to treat endocarditis caused by s. faecium in the rabbit model. s. faecium proved more resistant to penicillin than streptococcus faecalis. even more striking, however, was the resistance to in vitro synergism by combinations of penicillin and various aminoglycosides. at clinically achievable concentrations, penicillin-gentam ...1979113469
release of autolytic enzyme from streptococcus, faecium cell walls by treatment with dilute alkali.the autolytic enzyme (endo-beta-1,4-n-acetylmuramoylhydrolase) of streptococcus faecium (s. faecalis atcc 9790) was released in a soluble form from insoluble cell wall-autolytic enzyme complexes by treatment with dilute naoh at 0 degree c. treatment of cell wall-enzyme complexes, obtained from either exponential- or stationary-phase cells, with 0.008 to 0.01 n naoh gave maximum yields of autolytic enzyme activity. at a fixed concentration of naoh, the yield of autolysin increased with increasing ...1979110765
synthesis of aza homologues of folic acid.folic acid analogues containing an additional nitrogen atom between the phenyl ring and the carbonyl group of the side chain were synthesized. none of the compounds showed significant inhibitory activity against human lymphoblastic leukemia cells (ccrf-cem) in culture or against lactobacillus casei (atcc 7469) growth. against l1210 leukemia in mice, the aza homologue of folic acid, 4, and the aspartic acid analogue, 14, showed no increase in life span over control animals. these compounds were m ...1979109617
the amino acid sequence of dihydrofolate reductase from the mouse lymphoma l1210.the determination of the amino acid sequence of the dihydrofolate reductase (ec 1.5.1.3) from cells of the mouse lymphoma l1210 is described. the protein was cleaved by cyanogen bromide to produce the six fragments cb1 (residues 1 to 14), cb2 (residues 15 to 52), cb3 (residues 53 to 111), cb4 (residues 115 to 125), cb5 (residues 126 to 139), and cb6 (residues 140 to 186). one of the fragments, cb2, contained an internal homoserine derived from a methionine which was not cleaved by cyanogen bromi ...1979762074
coliforms and enterococci isolated from the intestinal tract of conventional mice.coliforms and enterococci were isolated from the intestinal tract of infant (12-day-old) and adult (6-to 8-week-old) conventional mice. eighty coliform isolates and eighty enterococcal strains were grouped according to their ability to ferment or hydrolyze various substrates. sixty-one of the coliform isolates were identified asescherichia coli. the remaining 19 strains were similar toe. coli, but did not produceβ-galactosidase. the enterococci belonged to two species:streptococcus faecium ands. ...197924232296
[in vivo and in vitro activity of streptococcus faecium extract on herpes simplex virus].the effects of substance or substance extracted from str. faecium sf 68 on hsv-1 are evaluated. the "in vivo" assay show that bacterial extract introduced i.p. in mice simultaneously with hsv-1 brought about 100% of survival, but bacterial extract after virus challenge brought about complete mortality of mice. "in vitro" assays show that bacterial extract reduce significantly pfu number. it seemed that str. faecium extract affected the virus at the stage of adsorption on the host cells.19806258615
primary structure of chicken liver dihydrofolate reductase.the complete covalent structure of dihydrofolate reductase from chicken liver is described. the s-carboxymethylated protein was subjected to cleavage by cyanogen bromide which produced five fragments. fragment cb2 contained an internal homoserine residue which was not cleaved by cyanogen bromide. sequences and ordering of the cyanogen bromide fragments were established by means of automated sequencer analyses of the fragments and from smaller peptides generated by proteolysis with trypsin and st ...19806766736
the biosynthesis of nascent membrane lipoteichoic acid of streptococcus faecium (s. faecalis atcc 9790) from phosphatidylkojibiosyl diacylglycerol and phosphatidylglycerol.phosphatidylkojibiosyl diacylglycerol functions as the acceptor of sn-glycerol 1-phosphate moieties from phosphatidylglycerol in the in vitro synthesis of the membrane lipoteichoic acid of streptococcus faecium (s. faecalis atcc 9790). the enzyme catalyzing this polymer-forming reaction is membrane-bound. the majority of the product is water-soluble, is excluded from sepharose 6b, and, after longer incubations, changes to a form that co-precipitates with protein upon exposure to a denaturing age ...19806768734
ornithine transcarbamylases. ordering of s-cyano peptides and location of characteristically reactive cysteinyl residues within the sequence.the peptides produced by cleavage of the s-cyano derivatives of the ornithine transcarbamylases (ornithine carbamoyltransferase, 2.1.3.3) from bovine liver, streptococcus faecalis atcc 11,420, and streptococcus faecium atcc 8043 have been isolated and aligned. their amino acid compositions and cooh-terminal sequences are reported. the cooh-terminal peptide (51 residues in the bovine enzyme; 66 residues in the bacterial enzymes) contains the essential sulfhydryl group.19806771285
survival of faecal streptococci in raw and pasteurised egg products.1. the ability of streptococcus faecalis and streptococcus faecium strains to survive in egg albumen and liquid whole egg before and after laboratory pasteurisation was studied. 2. pasteurisation of egg albumen caused a decrease in viable cells of less than 10-fold, while pasteurisation of whole egg caused decreases of more than 100-fold in only two of the eight strains studied. after growth in whole egg, some strains were more resistant to pasteurisation in whole egg. 3. strep. faecalis multipl ...19806772285
[reducing activity and differential thermal analysis of enterococci].the reducing activity of 100 streptococcus faecalis strains, 100 streptococcus faecium strains and 100 enterococcal strains were studied by the quantitative method. the study revealed that all mobile enterococci, in contrast to s. faecium, reduce 2,3,5-triphenyltetrazolium chloride with the formation of triphenylformasan. differential thermal analysis also indicated that s. faecalis, s. faecium and mobile enterococci had thermograms with definite mathematical characteristics and could be best di ...19806778026
[studies on the likelihood of growth of streptococcus faecium following thermal treatment in meat suspensions (author's transl)].a number of strains of enterococci was isolated from pasteurized meat products. two variants of streptococcus faecium (e1 and e20) took part in the present study. using these organisms, heating tests in suspensions of pork (sealed plastic pouches) were performed. mixtures of ingredients ('preparation of cooked ham') were added in the majority of experiments. dextrose was replaced by sorbitol in one experiment, by glycyrrhizin in another. following thermal treatment at 68.9 degrees c (various hea ...19807003809
microbiological properties of streptococcus faecium sf 68 strain and its relationships with other microorganisms. 19806786302
ecology of streptococcus faecium bacteriophage in chicken gut.the interaction in the chick gut between streptococcus faecium and its phage was examined. in conventional chicks, large numbers of s. faecium and phage were found in the cecum and smaller numbers were found in the anterior gut. in gnotobiotic chicks associated with s. faecium sy1 and its phage, there was no marked effect on bacterial numbers, but resistance to the phage rapidly developed. depression of chick growth caused by s. faecium strain sy1 was partially reversed by its phage.19807190368
lipids and lipoteichoic acid of autolysis-defective streptococcus faecium strains.two of four previously isolated autolysis-defective mutants of streptococcus faecium (streptococcus faecalis atcc 9790) incorporated substantially more [14c]glycerol into lipids and lipoteichoic acid than did the parent strain. consistent with increased accumulation of lipids and lipoteichoic acid, significantly higher levels of phosphorus were found in the corresponding fractions of the two mutant strains than in the wild type. although the autolysis-defective mutant strains contained the same ...19807380808
streptococcus faecium-derived antibacterial substance antagonistic to bifidobacteria.an antagonistic strain of streptococcus faecium was isolated from human feces, and it displayed a marked inhibition of bifidobacteria on agar plates. in liquid culture this isolate produced an antibacterial substance that can be partially purified by ammonium sulfate precipitation followed by gel filtration and ion-exchange chromatography. its activity was assayed by the inhibition of growth of bifidobacterium longum. the substance was sensitive to digestion by proteolytic enzymes and alpha-amyl ...19807416752
chromatographic purification from streptococcus faecium extract of a factor active on picornaviridae."in vitro" antiviral activity against picornaviridae and the trials for purification from str. faecium extract of a factor responsible of these effects are reported. fractionation on bio-gel p-150 and on deae-cellulose column and analytical methods for protein and aminosugars were used. present results demonstrate an antiviral activity of str. faecium extract against picornaviridae. virus inhibiting activity is not correlated with the majority of the folin reacting proteins, which are present in ...19817326116
the colonization of streptococcus faecium in human intestinal tract after oral administration.the colonizing ability of streptococcus faecium strain sf 68 at different levels of the gastrointestinal tract was assessed in ten patients. they were orally treated with a preparation containing the bacteria in lyophilized form for three days. during an abdominal surgical operation a sample of bacterial content of jejunum, ileum and colon was taken and cultured. the streptococcus faecium was detected in all treated patients in a quite high concentration compared to the counts of both aerobic an ...19817340850
bacteriocin and hemolysin from streptococcus faecium.the bacteriocin and hemolysin produced by a streptococcus faecium strain were partially separated after gel filtration on ultrogel aca-22. the molecular weight of bacteriocin was approximately 300,000, and that of hemolysin was 220,000. non-bacteriocinogenic mutants retained the hemolytic activity. production of hemolysin required glucose, whereas that of bacteriocin did not.19817342879
mode of elongation of the glycerol phosphate polymer of membrane lipoteichoic acid of streptococcus faecium atcc 9790.specific degradation of membrane lipoteichoic acid of streptococcus faecium atcc 9790 by a phosphodiesterase from aspergillus niger and by periodate oxidation has demonstrated that the enzymatic synthesis of the glycerol phosphate polymer of the molecule occurs by an external elongation system. evidence of this type of mechanism was obtained with lipoteichoic acid synthesized in vivo or in vitro by differential radioisotope labeling techniques. the glycerol phosphate repeating units were transfe ...19817240097
attachment of streptococcus faecium, to the duodenal epithelium of the chicken and its importance in colonization of the small intestine.the counts of streptococcus faecium sy1 in the duodenums of gnotobiotic chicks exceeded the counts in their crops, indicating that multiplication was occurring in the anterior small intestine. this growth was related to adhesion to the gut wall which could be demonstrated by viable counts of macerated washed duodenal tissue. scanning electron microscopy demonstrated that adhesion occurred in restricted areas on the surface of the villus, and transmission studies showed the presence of a thick ex ...19817247397
the gut microflora and the uptake of glucose from the small intestine of the chick.1. chicks whose growth rate had been depressed either by a fully conventional flora or by association with a bile acid deconjugating strain of streptococcus faecium and/or a filterable agent from chicken droppings showed no significant reduction in uptake of 3-0-methyl-alpha-d-glucopyranose compared with germ-free birds. 2. association with a microflora increased the weight of the gut per unit length.19817260707
correlation of growth depression of chicks with the presence of streptococcus faecium in the gut. 19817275868
surface tension-like forces determine bacterial shapes: streptococcus faecium.the same tendency that causes soap bubbles to achieve a minimum surface area for the volume enclosed seems to account for many of the features of growth and division of bacteria, including both bacilli and cocci. it is only necessary to assume that growth takes place in zones and that only in these zones does the tension caused by hydrostatic pressure create the strain that forces the cell to increase the wall area. the stress developed by osmotic pressure creates strains that significantly lowe ...19817320694
mode of antibiotic action of 4-hydroxy-3-nitrosobenzaldehyde from streptomyces viridans.the free ligand, deferroviridomycin a, and its iron(ii) complex, viridomycin a, were detected in culture supernatant fluids of streptomyces viridans 1671 and were structurally characterized as 4-hydroxy-3-nitrosobenzaldehyde and tris(4-hydroxy-3-nitrosobenzaldehydato-n3,o4)ferrate(ii), respectively. we investigated the antibiotic activity of the above compounds and of the chemically synthesized bis copper(ii), tris cobalt(iii), and tris nickel(ii) complexes against escherichia coli nihj, salmone ...19816805420
effect of solar radiation and predacious microorganisms on survival of fecal and other bacteria.the effect of solar radiation and predacious microorganisms on the survival of bacteria of fecal and plant origin was studied. the decline in the numbers of escherichia coli cells in estuarine water samples was found to be significantly greater in the presence of both naturally occurring microbial predators and solar radiation than when each of these factors was acting independently. the effect of solar radiation on microbial predators was negligible, whereas the susceptibility of bacteria to li ...19817020590
new synthesis of n-[4-[[(2-amino-4(3h)-oxopyrido[3,2-d]pyrimidin-6-yl)methyl]amino]benzoyl]-l-glutamic acid (8-deazafolic acid) and the preparation of some 5,6,7,8-tetrahydro derivatives.previously, 8-deazafolic acid (17) was shown to be a potent inhibitor of the folate-dependent bacteria, streptococcus faecium (atcc 8043) and lactobacillus casei (atcc 7469), and to have activity against lymphoid leukemia l1210 in mice. to examine the 5,6,7,8-tetrahydro derivatives, a new synthesis of 17 was developed from 8-deaza-2,4-dichloro-6-methylpteridine. treatment of the latter with aqueous base gave the corresponding pteridin-4(3h)-one, which was aminated with ammonia to give 8-deaza-6- ...19816948961
carbon-13 nuclear magnetic resonance study of protonation of methotrexate and aminopterin bound to dihydrofolate reductase.methotrexate, aminopterin, and folate have been synthesized with 90% enrichment of c-2 with 13c. 13c nuclear magnetic resonance has been used to examine the state of protonation of the pteridine ring of these compounds under various conditions and gives much more clear-cut results than most other methods. for the free compounds the following pk values were obtained: methotrexate, 5.73 +/- 0.02 (n-1); aminopterin, 5.70 +/- 0.03 (n-1); folic acid, 2.40 (n-1) and 8.25 +/- 0.05 (n-3, o-4 amide group ...19817284303
chemical mechanism of the reaction catalyzed by dihydrofolate reductase from streptococcus faecium: ph studies and chemical modification.the variation with ph of the kinetic parameters associated with dihydrofolate reductase from streptococcus faecium has been used to gain information about the chemical mechanism of the reaction catalyzed by the enzyme. the ph dependence of log v/k for dihydrofolate showed that a group with a pk value of 4.7 must be ionized and that a group with a pk value of 6.6 must be protonated for activity. temperature and solvent perturbation studies indicate that these groups are probably the carboxyls of ...19817306491
turbidimetric assay for virginiamycin in feeds and premixes.a turbidimetric assay method applicable to virginiamycin at level ranging from 5 g/ton in feeds to 50% in a premix is described. incubation period is 4 h. test organism is streptococcus faecium atcc 8043. on 6 levels of feed-grade material, the overall mean recovery was 6.75% standard recovery studies resulted in rsd values ranging from 2.01 to 3.88% and a mean standard recovery of 100%.19816785271
[studies on the usefulness of different disinfectants for the aerosol disinfection of surfaces (author's transl)].in a glove-box made of stainless steel germ-carriers of lime-wood and aluminium were layed out after having been contaminated with different vegetative bacteria (staphylococcus aureus, streptococcus faecium, pseudomonas aeruginosa, proteus mirabilis). disinfectant aerosols of several germicidal substances belonging to different chemical groups were brought into the glove-box. the aerosol was produced by a commercial generator. the following substances proved to have a good disinfectant effect un ...19816792816
susceptibility of enterococci and listeria monocytogenes to n-formimidoyl thienamycin alone and in combination with an aminoglycoside.the susceptibilities of 12 strains of enterococci and 10 stains of listeria monocytogenes to n-formimidoyl thienamycin were determined by a standard broth dilution method. minimal inhibitory concentrations for l. monocytogenes strains were less than 0.25 micrograms/ml. as a group, strains of streptococcus faecium were less susceptible than streptococcus faecalis strains, but even for the latter, the minimal inhibitory concentrations were slightly greater than those previously reported. minimal b ...19816794445
nuclear magnetic resonance study of dihydrofolate reductase labeled with [gamma-13c]tryptophan.dihydrofolate reductase isozyme 2 of streptococcus faecium has been labeled with 13c in the c gamma position of tryptophan residues by growing the organism on a defined medium containing l-[gamma-13c]tryptophan (90% 13c). the 13c nuclear magnetic resonance (nmr) spectrum of the enzyme shows four well-resolved resonances which have nuclear overhauser enhancements of 1.1-1.3. values of t1 (spin-lattice relaxation time) and t2 (spin-spin relaxation time) are significantly less than predicted for an ...19816796111
resistance to macrolide-lincosamide-streptogramin antibiotics in enterococci from the intestines of animals.macrolide-lincosamide-streptogramin group b (mls) resistant strains were found among enterococci isolated from caeca of poultry, pigs and cattle. the percentage of mls resistance among the poultry strains was 70 per cent. the streptococcus faecium strains were more susceptible than the other enterococcal strains to virginiamycin, a member of the streptogramin class of antibiotics. this was due to higher susceptibility of the s faecium strains to the virginiamycin component m which belongs to the ...19826813931
a cell-free system for streptococcus faecium for studies on the biosynthesis of triterpenoid carotenoids.a cell-free enzyme extract from streptococcus faecium unh 564p has been prepared. the extract incorporates either [2-14c]mevalonic acid (mva) or [1-14c]isopentenyl pyrophosphate (ipp) into squalene and the carotenoids of the bacterium. atp and manganese ion were found to be absolute requirements for mva incorporation by the extract. only manganese ion was found to be an absolute requirement for ipp incorporation by the extract. other cofactors including magnesium ion, glutathione, potassium fluo ...19826749265
evaluation of a rapid system for species identification of alpha-hemolytic streptococci.a new 4-h commercial system (api 20s; analytab products, plainview, n.y.) for the identification of streptococci was compared with the conventional biochemical profile method in the species identification of alpha-hemolytic streptococci. a total of 194 clinical isolates (including 74 isolated from blood cultures, 64 isolated from wound cultures, and 56 isolated from respiratory cultures) and 20 reference strains were tested. only 4 of the 20 reference strains were correctly identified to species ...19826752191
effect of streptococcus faecium c-68 in control of escherichia coli-induced diarrhea in gnotobiotic pigs.streptococcus faecium was fed to prevent colibacillosis in gnotobiotic pigs. three strains of escherichia coli were used. with strain o:k103, 987p:nm in pigs fed s faecium before the e coli challenge exposure, the pigs exhibited less severe diarrhea, recovered earlier, and produced better weight gains than did pigs given e coli only. escherichia coli strains o157:k88ac:h19 and o8:k87, k88ab:h19 were more virulent. pigs fed s faecium and challenge exposed with these 2 strains of e coli developed ...19826762120
resistance to beta-lactam antibiotics in streptococcus faecium.clinical isolates of streptococcus faecium are characteristically resistant to beta-lactam antibiotics. two strains, selected for hypersusceptibility to penicillin, were derived from normally resistant isolates treated with novobiocin. these strains were also found to be hypersusceptible to other beta-lactams. differences in beta-lactam susceptibility between the original isolates and the hypersusceptible strains could not be attributed to alterations in penicillin-binding protein affinities, an ...19826927638
inexpensive treatment of frozen dairy products for membrane filtration.treatment of frozen dairy products with trypsin and tween 80 before membrane filtration for microbiological analysis was faster and cost less than treatment with streptomyces griseus protease-tween 80. viable cell counts so escherichia coli, staphylococcus aureus, streptococcus faecium, and salmonella typhimurium were not reduced.19827036901
lipoteichoic acid, a major amphiphile of gram-positive bacteria that is not readily extractable.commonly used procedures effected the extraction of only 10% of the lipoteichoic acid of stationary-phase cells of staphylococcus aureus and streptococcus faecium, unless the cells were first disrupted.19827054150
bile acid transformation by the intestinal flora and cholesterol saturation in bile. effects of streptococcus faecium administration.in 8 normal subjects the daily administration for 30 days of at least 750 x 10(6) streptococcus faecium, a bacteria producing substances acting against clostridia and other intestinal microorganisms reduced the cholesterol saturation and the molar percentage of deoxycholic acid (dca) in bile. the percentage of cholic acid (ca) and chenodeoxycholic acid (dca) increased significantly in feces, whereas lithocholic acid (lca) decreased from 49.2 to 40.5%. in vitro fecal samples of subjects taking s. ...19827095315
the biosynthesis of triterpenoid carotenoids in streptococcus faecium unh 564p.cell-free enzyme preparations from streptococcus faecium unh 564p and phycomyces blakesleeanus strain c5-car10(-) were used to study the incorporation of [14c]isopentenyl pyrophosphate and either all-trans-[4,8,12-3h]farnesyl pyrophosphate (fpp) or all-trans--[4,8,12,16-3h]geranylgeranyl pyrophosphate (ggpp) into squalene and the carotenoids of the organisms. it was found that the triterpenoid (c30) carotenoids of s. faecium are formed by condensation of two molecules of fpp similar to squalene ...19827116207
nuclear magnetic resonance study of interaction of ligands with streptococcus faecium dihydrofolate reductase labeled with [gamma-13c]tryptophan. 19827126550
susceptibility of fecal streptococci of poultry origin to nine growth-promoting agents.the minimal inhibitory concentrations of nine growth-promoting agents were determined by an agar-dilution method against 66 bile-tolerant streptococcal (8 streptococcus faecalis, 23 streptococcus faecalis subsp. liquefaciens, 15 streptococcus faecium, and 20 carboxyphilic streptococci) strains isolated from the ceca of 52 chickens on 19 farms. avoparcin was equally active on all groups. the natural susceptibilities against the other substances differed among the groups studied. bacitracin and vi ...19827149716
[treatment of acute diarrhea in pediatrics with streptococcus faecium: results of a double blind study]. 19827163985
the role of surface stress in the morphology of microbes.the shapes of many prokaryotes can be understood by the assumption that the cell wall expands in response to tension created by the osmotically derived hydrostatic pressure. different organisms have different shapes because wall growth takes place in different regions. a previous paper (koch et al., 1981 a) considered the simplest case of prokaryotic growth, i.e. that of streptococcus faecium. in the present paper, an elaboration of this theory is applied to two further cases - the more perfectl ...19826809889
the atp-dependent ca2+-pumping system of streptococcus faecium. 19826220642
conjugative r plasmids in streptococcus faecium (group d).ten isolates of streptococcus faecium were found to be resistant to penicillin, tetracycline, macrolides and related drugs, streptomycin, and kanamycin, and four strains were resistant to chloramphenicol. six of these 10 strains transferred all their resistance markers (except penicillin) by conjugation at a low frequency (10(-7) to 10(-9)). several plasmids of different molecular weights were found in each of the wild-type strains. in 5 of 11 transconjugant strains, r plasmids were detected whi ...19826285813
inhibition of clostridium difficile by faecal streptococci.the inhibitory activity of seven strains of faecal streptococci against 34 strains of clostridium difficile was examined in vitro after growth of the streptococci for 24 and 48 h. all strains of c. difficile were inhibited at 48 h but at 24 h the inhibition was variable. streptococcus faecium, a group d streptococcus and an ungroupable streptococcus exhibited the most striking inhibitory activity. lowering of ph of the medium occurred at the site of inhibition, but the ph change alone did not ex ...19827175918
polyclonal lymphocyte activators: adjuvant activity of a crude extract of streptococcus faecium.a crude extract of streptococcus faecium, prepared according to krämer and bradis method, was utilized to further extend our previous research on polyclonal lymphocyte activators. experiments were performed using jerne's pfc method on 12 week-old c3h/fej mice immunized with sheep red blood cells to study the adjuvant activity of the crude extract by varying its dose, times of administration, and administration route (intraperitoneal, intravenous, subcutaneous). the extract, containing cell membr ...19827187352
the ecology of the streptococci.all species of streptococci are divided into several groups according to the ecological niches they occupy. members of the lactic acid group are found only in the plant environment and the dairy. members of the pyogenic group and the buccal and intestinal residents of the subthermophilic group are found in intimate association only with homeothermic hosts. members of the virulent pyogenic group, such asstreptococcus pyogenes, s. equi, ands. infrequens, are restricted to single hosts-the human, t ...198224226053
[experimental study on synergism between cefotaxime and ampicillin against streptococcus d group].cefotaxime (ctx) disks and ampicillin (abpc) disks exhibited synergism against 24 strains of streptococcus d group isolated from various sources in our hospital. we were interested in these synergism effects and compared them with the combination index. twenty-two out of the 24 strains examined exhibited synergism, and were identified as streptococcus faecalis by the api strep system. we divided them into 4 groups (combination index: 19, 15, 11, 9) according to the degree of synergism. another 2 ...19836302344
a note on the identity and properties of the spoilage microflora of chub-packed luncheon meat stored at ambient temperature.the principal spoilage bacteria isolated from chub-packed luncheon meat stored at 25 degrees c have been identified as strains of bacillus licheniformis and streptococcus faecium. bacillus licheniformis alone is responsible for those degradative changes (surface softening and discolouration, gas production and eventual product liquefaction) regarded as overt product spoilage. streptococcus faecium metabolizes carbohydrate homofermentatively, and the resultant accumulation of lactic acid causes s ...19836652582
the effect of feeding streptococcus faecium upon escherichia coli induced diarrhea in gnotobiotic pigs.streptococcus faecium (sf) was fed to gnotobiotic pigs to control colibacillosis. three strains of escherichia coli (ec) were used. strain 0:k103,987p:nm of ec fed to pigs without sf developed severe diarrhea which persisted for several days. those pigs given sf and ec had less diarrhea, recovered earlier, and had better weight gains than ec only pigs. two other strains of ec (0157:k88ac:h19 and 08:k87,k88ab:h19) which were more virulent developed severe diarrhea and death in 5 of 8 pigs given e ...19836361858
folate analogues. 21. synthesis and antifolate and antitumor activities of n10-(cyanomethyl)-5,8-dideazafolic acid.a close analogue of the antileukemic agent 5,8-dideaza-n10 propargylfolic acid (2) was synthesized by replacing the propargyl moiety of 2 with a cyanomethyl group. this compound, n10-(cyanomethyl)-5,8-dideazafolic acid (3), was evaluated for its antifolate and antitumor activities in several biological test systems. alkylation of diethyl n-(4-aminobenzoyl)-l-glutamate with bromoacetonitrile gave diethyl n-[4-[(cyanomethyl)amino]benzoyl]-l-glutamate (7). reaction of 7 with 2 amino-6-(bromomethyl) ...19836403710
[numerical classification of enterococci].the taxonomic analysis of enterococci by a mathematical method has revealed that these organisms are subdivided, according to their properties, into three taxons; of these, two taxons correspond to the species known as streptococcus faecalis and streptococcus faecium, while the third taxon, sharply different from the rest, comprises mobile enterococci which can be probably regarded as a separate species and differentiated from the other two species by a number of characteristics.19836404074
cell wall assembly during inhibition of dna synthesis in streptococcus faecium.growth sites which are bounded by raised wall bands can be observed in electron micrographs of replicas of streptococcus faecium. when mitomycin c was added to an exponential-phase culture doubling in mass every 64 min, dna synthesis was inhibited, and eventually cell division stopped. the growth sites formed before and after inhibition of dna synthesis enlarged until they contained about 0.25 micron3 of cell volume, at which point they ceased to increase in size. when these sites approached thi ...19836408063
folate analogues. 22. synthesis and biological evaluation of two analogues of dihydrofolic acid possessing a 7,8-dihydro-8-oxapterin ring system.two analogues of dihydrofolic acid possessing a 7,8-dihydro-8-oxapterin ring system have been synthesized and evaluated for their antifolate activities. these compounds, n-[(2-amino-4-hydroxy-7,8-dihydro-8-oxa-6-pteridinyl)benzoyl]-l-glutamic acid (3) and n-[[(2-amino-4-hydroxy-7,8-dihydro-8-oxa-6-pteridinyl) methyl]benzoyl]-l-glutamic acid (4), were synthesized by reacting the appropriately substituted alpha-halo ketones with 2,5-diamino-4,6-dihydroxypyrimidine (2). elaboration of p-carbomethox ...19836410065
identification of a streptococcal penicillin-binding protein that reacts very slowly with penicillin.penicillin-binding protein (pbp) 5 of streptococcus faecium atcc 9790 has an unusually low affinity for penicillin (50% binding occurred at a penicillin level of 8 micrograms/ml after 60 min of incubation, and the protein only became labeled after 20 min of incubation with high concentrations of radioactive penicillin). pbps with similar properties are carried by strains of streptococcus durans, streptococcus faecalis, and streptococcus lactis but not by strains of groups a, b, c, and g streptoc ...19836411688
molecular basis for the interaction of polyglutamates of folic acid and its analogs with dihydrofolate reductase.fluorimetric titration has been used to measure the dissociation constants for the complexes of folate, pteroyltriglutamate and pteroylheptaglutamate with dihydrofolate reductase purified from lactobacillus casei, streptococcus faecium (isoenzyme 2) and bovine liver. effects of ph, temperature, salt concentration and second ligands have been examined. the method is shown to be unsuitable for methotrexate complexes. the polyglutamates do not bind more tightly than folate to the s. faecium reducta ...19836412519
medium-dependent zone size discrepancies associated with susceptibility testing of group d streptococci against various cephalosporins.mueller-hinton (mh) agar media from various commercial sources, either supplemented or not supplemented with 5% sheep blood, were studied to determine their effect on disk diffusion susceptibility testing results obtained with 90 strains of group d streptococci and four cephalosporins. the cephalosporins investigated included cephalothin, cefamandole, moxalactam, and cefotaxime. results showed that a number of streptococcus faecalis and streptococcus faecium strains were susceptible to cephaloth ...19836415100
protonated state of methotrexate, trimethoprim, and pyrimethamine bound to dihydrofolate reductase.13c nuclear magnetic resonance (nmr) of methotrexate, trimethoprim, and pyrimethamine enriched 90% with 13c at c2 has provided a sensitive means of detecting the state of protonation of the heterocyclic rings of these inhibitors. in each case, protonation of n1 causes an upfield movement of the chemical shift of c2 by more than 6 ppm. by this method it has been shown that, at ph values up to 9.2, methotrexate is bound to bovine liver dihydrofolate reductase with n1 of the inhibitor protonated, j ...19836416176
division blocks in temperature-sensitive mutants of streptococcus faecium (s. faecalis atcc 9790).two hundred nine temperature-sensitive growth or division (or both) mutants of streptococcus faecium atcc 9790 were isolated. these strains were examined for timing of the division block in the cell division cycle. about 42% of the isolates were blocked at terminal stages of cell division. a second large group appeared to be blocked at various stages of septation. only five of the temperature-sensitive isolates were blocked at a stage before the completion of chromosome replication. thirty tempe ...19836417107
the effect of dietary penicillin on the growth of gnotobiotic chickens monoassociated with streptococcus faecium. 19836831273
initiation of wall assembly sites in streptococcus faecium.in electron micrographs of replicas of streptococcus faecium, sites of wall growth are located between pairs of raised equatorial bands. analysis of cells taken from cultures with mass doubling times between 30 and 125 min indicates that rounds of wall synthesis are initiated at a time close to division, which is temporally unrelated to the initiation or termination of chromosome replication. growth sites are initiated at a relatively constant volume independent of growth rate when the volume co ...19836841311
streptococcus faecium atcc 9790 penicillin-binding proteins and penicillin sensitivity are heavily influenced by growth conditions: proposal for an indirect mechanism of growth inhibition by beta-lactams.the effects of variations in growth conditions on the penicillin response of streptococcus faecium atcc 9790 were studied. changes in the growth temperature and medium composition were found to cause striking changes in the bacterial generation time, cellular penicillin sensitivity (minimum inhibitory concentration), sensitivity of peptidoglycan synthesis to inhibition by penicillin, rate of autolysis, and labeling pattern of penicillin-binding proteins. however, no constant relationship between ...19836841320
increased carbohydrate substitution of lipoteichoic acid during inhibition of protein synthesis.decreases in electrophoretic mobilities of intracellular lipoteichoic acid, intracellular deacylated lipoteichoic acid, and extracellular deacylated lipoteichoic acid were observed during inhibition of protein synthesis in streptococcus faecium after exposure to chloramphenicol or valine deprivation. increased carbohydrate content, and thus an increased mass-to-charge ratio, rather than changes in ester alanine content or novel fatty acid substitutions, appeared to account for the decreased elec ...19836863217
purification and some properties of the endogenous, autolytic n-acetylmuramoylhydrolase of streptococcus faecium, a bacterial glycoenzyme.the latent form of the endogenous, autolytic n-acetylmuramoylhydrolase of streptococcus faecium atcc 9790 was purified to near homogeneity by affinity chromatography on concanavalin a-sepharose 4b. the latent enzyme had mr approximately 130,000 on sodium dodecyl sulfate-gel electrophoresis. upon proteinase treatment (trypsin or endogenous proteinase), the latent form is converted to an active form mr approximately 87,000. the enzyme was shown to be glycoprotein, containing monomeric and oligomer ...19836874701
association of rna with thymidylate synthase from methotrexate-resistant streptococcus faecium.thymidylate synthase (5,10-methylenetetrahydrofolate:dump c-methyltransferase, ec 2.1.1.45) from methotrexate-resistant streptococcus faecium has a uv absorbance peak at 259 nm and stains with acridine orange because of the presence of rna on the protein. material having an absorbance peak at 254 nm, obtained from the enzyme by phenol extraction, is degraded by treatment with pancreatic rnase, t1 rnase, and alkali but is stable to dnase. dowex-1 chromatography of the pure enzyme yields two polyn ...19836189121
rapid identification of enterococci.a 4-h method was devised to differentiate the non-beta-hemolytic streptococci into three categories: enterococci, group d nonenterococci, and viridans streptococci. all of the streptococcus faecalis, 90% of the streptococcus faecium (enterococci), and 96% of the streptococcus bovis biotype i (group d nonenterococci) cultures were correctly identified by the 4-h method. the less commonly isolated group d cultures had lower rates of correct identification by this method. none of the viridans strep ...19836643675
the ineffectiveness of tobramycin combination therapy in streptococcus faecium endocarditis.a patient required mitral valve replacement following ineffective antibiotic treatment of enterococcal endocarditis caused by streptococcus faecium. endocarditis had relapsed despite therapy with ampicillin and tobramycin for six weeks. a second relapse had occurred following treatment with penicillin and gentamicin. initial failure of antibiotic therapy may be related to the known lack of in vitro and in vivo synergy between penicillin and tobramycin against s. faecium. effective therapy of ent ...19836659563
folate analogues. 20. synthesis and antifolate activity of 1',2',3',4',5',6'-hexahydrohomofolic acid.the synthesis of 1',2',3',4',5',6'-hexahydrohomofolic acid (3), a close analogue of homofolic acid (2), has been carried out by replacement of the benzene ring of 2 with a cyclohexane ring. the synthetic methods employed here were based on the boon-leigh strategy to obtain products with unambiguous structures. based on a number of chemical and spectral observations, a tentative cis stereochemistry was assigned to the 1,4-substituents of the cyclohexane ring of both the homopteroate analogue 13 a ...19836827531
synthesis and antifolate properties of 10-alkyl-8,10-dideazaminopterins.the synthesis of 10-alkyl analogues of the potent antitumor agent 8,10-dideazaminopterin is described. alkylation of appropriate alpha-alkyl homoterephthalate esters with 2,4-diamino-6-(bromomethyl)-8-deazapteridine afforded 10-alkyl-10-carboxy-4-amino-4-deoxy-8,10-dideazapteroic acid diesters. ester cleavage and decarboxylation at c-10 were accomplished by heating with sodium cyanide in me2so at 170-180 degrees c to afford the 2,4-diamino-10-alkyl-8,10-dideazapteroic acids. the acids were coupl ...19846699882
isolation and characterization of soluble peptidoglycan from several strains of streptococcus faecium.two phenotypically autolysis-deficient strains of streptococcus faecium atcc 9790 were shown to produce high-molecular-weight, soluble, linear, uncross-linked peptidoglycan when incubated with benzylpenicillin in a wall medium which permits cell wall synthesis (wall thickening) but not balanced growth. this high-molecular-weight s-peptidoglycan was shown to have a molecular weight of 46,000 to 54,000, lack peptide cross-links, and be virtually devoid of accessory wall polymers. it was hydrolyzed ...19846746571
hydrolysis of soluble, linear, un-cross-linked peptidoglycans by endogenous bacterial n-acetylmuramoylhydrolases.soluble, linear, uncross-linked peptidoglycans, prepared from two autolysis-defective mutants of streptococcus faecium atcc 9790 and from micrococcus leuteus, were used as substrates for studies of hydrolysis by an n-acetylmuramoylhydrolase (muramidase). the kinetics of hydrolysis of these substrates and the ability of the muramidases isolated from s. faecium atcc 9790 and from two autolysis-defective mutants, lyt-14 and aut-3, to carry out transglycosylation reactions were compared with the act ...19846746572
acquisition of k:1-like antigen during terminal sepsis.this report describes a patient whose own and transfused k:-1 red cell populations became strongly k:1 during a terminal episode of sepsis due to a group d streptococcus organism, streptococcus faecium. subsequent in vitro studies using normal k:-1 red cells inoculated with that organism showed that it could render the red cells agglutinable by reagents containing igg anti-k1. in addition, disrupted s. faecium organisms rendered jkb-negative red cells agglutinable by those reagents.19846420953
rutin-induced beta-glucosidase activity in streptococcus faecium vgh-1 and streptococcus sp. strain frp-17 isolated from human feces: formation of the mutagen, quercetin, from rutin.a fecal isolate, streptococcus sp. strain frp-17, and strain vgh-1 of streptococcus faecium were shown to contain beta-glucosidases which converted rutin (quercetin-3-o-beta-d-glucose-alpha-l-rhamnose) to quercetin and were active against o-nitrophenyl-beta-d-glucose. the activity against rutin could be measured by increased mutagenicity in the ames assay or visualized on thin-layer chromatography plates. in both organisms, the beta-glucosidase activities were inducible by the addition of rutin ...19846424566
incubation temperature and faecal streptococci recovery from marine sediments.a comparative work was carried out on two different incubation temperatures that may be used for faecal streptococci recovery. analyses were made on sediments samples collected in the bay of naples in a larger survey of environmental pollution detection. results showed a selective effect of 44 degrees c temperature on the isolation of the streptococcus faecalis, streptococcus faecium and streptococcus durans species that may be considered properly faecal streptococci.19846427553
effect of oral administration of a variety of bacteria on depressed macrophage functions in tumour-bearing rats.in consideration of the well documented influence of normal microbial flora on the level of activation of macrophages, we evaluated the effects of oral administration of bacteria on rats with depressed macrophage functions. an oral, killed polyvalent vaccine (diplococcus pneumoniae types i, ii and iii, streptococcus haemolyticus, staphylococcus aureus and haemophilus influenzae), the live lyophilized streptococcus faecium and spores of bacillus subtilis, respectively, were administered orally to ...19846433774
species-specific irreversible inhibition of neisseria gonorrhoeae dihydrofolate reductase by a substituted 2,4-diamino-5-benzylpyrimidine.neisseria gonorrhoeae dihydrofolate reductase undergoes a time-dependent, irreversible inactivation by 2,4-diamino-5-[3,5-dimethoxy-4-(p-bromoacetamidophenoxy)benzyl] pyrimidine. the kinetics of inactivation are consistent with the reversible formation of an enzyme-inhibitor complex followed by covalent binding to the enzyme. the reversible component is competitive with dihydrofolate and has an inhibitor binding constant of 10 nm. irreversible inactivation proceeds as a pseudo first-order proces ...19846434542
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