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At least 19 recordsLinked to original sources
PubMed1976

Incorporation of double-labelled valine into delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine by Penicillium chrysogenum.

The incorporation of valine into the LLD-tripeptide, delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine, a precursor of penicillin, was studied by incubating mycelial mats of Penicillium chrysogenum Wis. 49-2105 with double labelled valines. L-valine was incorporated into the LLD-tripeptide without formation of an alpha, beta-didehydrovaline intermediate. Intact D-valine was not incorporated into the LLD-tripeptide.

Carbon Radioisotopes↗
PubMed1977

Solid phase synthesis and some hormonal activities of 1-deamino-4-L-valine-8-D-homolysine-and 1-deamino-4-L-valine-8-D-homoarginine-vasopressin.

1-Deamino-4-L-valine-8-DL-homolysine-vasopressin and protected 1-deamino-4-l-valine-8-D-lysine-vasopressin were synthesized by the solid phase method and were then converted into the title compounds (dVDHLVP and dVDHAVP) by tryptic digestion and epsilon-guanidination, respectively. The new hormone analogues exhibit only moderate antidiuretic potency, dVDHLVP 21 units/mg and dVDHAVP 31 units/mg, but since they are essentially devoid of pressor activity (o.o1 units/mg/ the A/P ratios are very high. In fact, dVDHLVP is the most specific antidiuretic agent in the lysine series known so far.

Amino Acid Sequence↗
PubMed1977

Hemoglobin S Travis: a sickling hemoglobin with two amino acid substitutions [beta6(A3)glutamic acid leads to valine and beta142 (h20) alanine leads to valine).

Hb S Travis is a previously undescribed sickling hemoglobin with two amino acid substitutions in the beta chain: beta6 Glu leads to Val and beta142 Ala leads to Val. The beta6 Glu leads to Val mutation imparts to Hb S Travis the characteristic properties of sickling hemoglobin, namely its association with erythrocyte sickling, the insolubility of the hemoglobin in the reduced form, and a minimum gelling concentration value identical to Hb S. Unlike Hb S, Hb S Travis exhibits an increased oxygen affinity and a decreased affinity for 2,3-bisphosphoglycerate and inositol hexakisphosphate. In addition, the variant hemoglobin's tendency to autoxidize and its mechanical precipitability suggest that there are conformational differences between Hb S and Hb S Travis.

Alanine↗
PubMed1976

Relationship of the pool of intracellular valine to protein synthesis and degradation in cultured cells.

To explore the role of the pool of intracellular free valine in the processes of protein synthesis and protein degradation, cultured hepatoma (HTC) cells were incubated in media containing varying concentrations of L-valine, under conditions of constant rates of protein synthesis and protein breakdown, and at steady state levels of intracellular valine specific radioactivities. Two types of experiments were compared: in the first (designated "incorporation experiment"), unlabeled cells were exposed to [3H]valine for a short period of time. In the second (termed "reincorporation experiment"), cells were prelabled with [3H]valine and then incubated for a brief period with media containing different concentrations of unlabeled valine; reincorporation of [3H]valine was calculated by the difference between the release of [3H]valine from labeled cellular proteins at low valine concentrations, and the maximal rate of the release at high valine concentrations. In both types of experiments, the rates of [3H]valine incorporation or reincorporation were compared with the respective specific radioactivities of free intracellular valine. In the incorporation experiment, the rates of [3H]valine incorporation into protein calculated by the intracellular specific radioactivities were not constant, but showed an upward deviation at low valine concentrations. This is in agreement with the results of Mortimore, G.E., Woodside, K.H., and Henry, J.E. ((1972) J. Biol. Chem. 247, 2776-2784) in the perfused rat liver. By contrast, in the reincorporation experiment, the calculated rates of [3H]valine reincorporation based on intracellular specific radioactivities were constant throughout the range of valine concentrations. The constant value of calculated valine reincorporation was lower by 30 to 50% than the calculated rate of valine incorporation at high valine concentrations. The following model is proposed to explain these results. There is one common pool of free intracellular valine, but there are two sites where valyl-tRNA can be formed. The first is an internal site that utilizes valine from the intracellular pool, and the second is an external (possibly membranous) system that converts extracellular valine directly to valyl-tRNA. Valine originating from protein degradation flows into the intracellular pool, from which it can be reutilized by the internal system. According to these assumptions, in the incorporation experiment and at low valine concentrations, the specific activity of valyl-tRNA is higher than that of the intracellular pool of free valine, due to the contribution of the external system. On the other hand, in the reincorporation experiment the specific activity of extracellular valine is negligible in comparison with that of the intracellular pool. Therefore, in this case the specific activity of valyl-tRNA is proportional to that of the intracellular pool, with a constant dilution by unlabeled valine of extracellular origin...

Cell Line↗
PubMed1976

Leucine, isoleucine and valine interactions in turkey poults.

In four experiments, the interactions of leucine, isoleucine and valine in turkey poults were studied. The additon of 1.50% excess leucine to a 22% protein starter diet, marginal in isoleucine and valine, depressed growth. This growth depression was corrected by the addition of valine and isoleucine. The addition of the excess leucine caused a decrease in plasma valine and isileucine concentrations in experiments 3 and 4, and plasma valine concentration in experiment 1. The addition of valine caused a marked linear increase in plasma valine with little or no effect on plasma isoleucine. The addition of isoleucine to the diet caused an increase in plasma isoleucine. Plasma valine, however, was decreased by the addition of isoleucine to a high-leucine diet. It is concluded that interactions exist in turkey poults between leucine-valine, leucine-isoleucine and isoleucine-valine and that the growth reduction caused by added leucine can be partly alleviated by addition of valine or by valine plus isoleucine, but not be isoleucine alone.

Animal Feed↗
PubMed1978

Valine metabolism in normal and chronically uremic man.

Valine metabolism was investigated in five normal and three nondialyzed chronically uremic subjects eating 40 +/- SEM 1 and 53 (range 40 to 80) protein diets respectively, in a metabolic research unit. Subjects were injected iv with a tracer dose of L-valine-1-14C while they fasted, and specific activity of plasma valine-14C and expiration of 14CO2 were monitored for two hours. Plasma valine was significantly lower in the uremic patients than in the normal subjects (P less than 0.05). In the uremic patients, specific activity of plasma valine fell less rapidly and remained higher, and expiration of 14CO2 was not different from normal subjects. A two-pool model for valine metabolism was derived which indicated that in uremic patients there was a significant decrease in both valine pools and in the rate of irreversible loss, i.e., valine incorporated into larger molecules, degraded, or excreted. Valine degradation was estimated to be decreased in the uremic patients.

Adult↗
PubMed1977

Valine requirement of the growing kitten.

The valine requirement of the kitten was studied using a crossover design with two groups of three weanling kittens. The kittens were fed a semipurified diet containing only free amino acids as a source of nitrogen containing 0.0%, 0.6%, or 1.8% valine. The mean +/- SE of the linear components of growth (g/day) of the six kittens were respectively:-13.8 +/- 1.7, 17.3 +/- 4.8, and 15.3 +/- 2.6. Corresponding food intakes were 26.0 +/- 3.9, 50.4 +/- 2.5, and 44.0 +/- 1.5. Nitrogen balance was positive with the same amount retained for the two valine-containing diets while nitrogen balance was negative for the kittens fed the valine-free diet. Plasms valine dropped markedly when the dietary valine was decreased from 1.8% to 0.6% (363 +/- 59 versus 66 +/- 13 nmole/ml), and was further decreased (33 +/- 13) when the valine-free diet was fed. It does not appear that the valine requirement of the kitten exceeds 0.6% of a diet containing 25% fat. These results support the hypothesis that the high protein requirement of the kitten is not a result of a high requirement for all the essential amino acids, but a result of a high "nitrogen" requirement.

Amino Acids↗
PubMed1977

Direct evidence for synthesis of valine in man.

Plasma valine and 13C-valine concentrations were measured in 2 healthy volunteers and 2 uraemic patients during and after a 3-hour intravenous infusion of the 13-c-labelled alpha-keto-acid analogue of valine. Plasma-valine increased by 23-43%. 13C-valine accounted for most of the early increase, but for less than 30% of the increase 1 hour after infusion. It was concluded that valine had increased by 2 mechanisms with different time courses. Initially, transamination of the infused ketoacid predominated, confirming directly for the first time that the essential aminoacid valine can be synthesised in-vivo both in health and uraemia. The previously unsuspected second mechanism was quantitatively more important but slower in ooperation; it may prove to be the key to understanding the metabolic effects of essential aminoacid precursors.

Adult↗
PubMed1979

Metabolism of [U-14C; 2,3-3H]-L-valine by the isolated perfused goat udder.

Two lactating mammary glands excised from 2 goats were perfused for several hours in the presence of [U-14C; 2,3-3H]-L-valine and received adequate quantities of glucose, acetate and amino acids. In the synthesized milk 96 and 89% respectively of the casein valine was derived from free plasma valine. Valine was extensively catabolized by mammary tissue, resulting in a considerable 14CO2 production and in the incorporation of 14C into milk citric acid and to a lesser extent into casein aspartic acid and glutamic acid. About 30% of the valine molecules which were taken up by the mammary gland were oxidized to CO2 and 70% were incorporated in casein as valine residues. About 10% of the plasma valine molecules were reversibly transaminated during one passage through the udder. An important amount of radioactivity of plasma was present in unknown metabolites. Only 7% of this activity was localized in isobutyrate. The radioactivity of total milk fat was very low. Mainly iso-14:0, iso-16:0 and 15:0 were labelled.

Animals↗
PubMed1978

The neurotoxicity of valine deficiency in rats.

When valine, an essential amino acid, was withdrawn from the diet of weanling rats, the animals rapidly developed a unique pattern of neurological symptoms characterized by head retraction, staggering and aimless circling. At necropsy degenerative changes were most prominent in the neurons of the red nuclei, brain stem structures which modulate motor function. To explore the pathogenesis of the neurotoxicity associated with valine deficiency, we fed rats purified diets deficient in valine alone or in valine plus other branched chain and neutral amino acids, and we examined brain tissues by light microscopy. Motor disfunction and red nuclei damage occurred only in rats fed diets lacking valine alone and not in rats fed diets lacking all three branched chain amino acids. These results suggest that the neurotoxicity of valine deficiency results from amino acid imbalance rather than from lack of dietary valine per se.

Animals↗
PubMed1976

[L-valine transport by the actinomycete Actinomyces species 26-115, the producer of actinomycin C].

Transport of L-valine by Actinomyces species 26-115, an organism producing actinomycin C depended on L-valine concentration in the medium and temperature and required a source of intrinsic energy. Km for L-valine transport was 3.5.10(-6)--6.0.10(-6) M. It somewhat differed from experiment to experiment. The above system transported also other neutral amino acids. L-isoleucine was a competing inhibitor of L-valine transport. The transport of L-valine was stereospecific. The activity of the transport system was regulated by the intracellular content of L-valine. Probably because of this the amino acid transport depended on the culture age, so far as the level of free valine in the mycelium at various stages of development was different.

Actinomyces↗
PubMed1977

[Source of valine for protein V biosynthesis in a producer of actinomycin C].

The specific activity of 14C-valine in valyl-tRNA formed during incubation of the actinomycin C-producing organism with 14C-valine was constant and lower than that of the whole cell pool. The constancy of the valyl-tRNA was indicative of the presence of a separate compartment for the valine pool used for protein biosynthesis. A lower specific activity of valine in valyl-tRNA as compared to that of the whole cell pool may be indicative of a low rate of valine metabolism in such separate compartment with exogenic 14-valine or a higher concentration of free valine in it as compared to the specific activity of this amino acid at average per cell.

Actinomyces↗
PubMed1978

Production of valine by a Bacillus sp.

A bacterium isolated from Burdwan (India) soil was found to accumulate L-valine in the growth medium and identified to be a strain of Bacillus subtilis. The strain is able to grow and accumulate valine in a purely synthetic medium, but supplementation of the synthetic medium with either Casamino acids or yeast extract or with both, significantly improves the yield. The entire fermentation period can be divided into a growth phase and a production phase, which can be prolonged by adjustment of pH to the neutral range. Among the different carbon and nitrogen sources tested glucose at 8.5% and L-glutamic acid at 0.8%, respectively, were found most suitable. Cane sugar molasses tested as a substitute for glucose significantly stimulated growth but valine production was less. Different vitamins tested stimulated growth and valine yield and an inoculum level of 10% (v/v) of the medium was found to be optimal. The yield of valine under optimal conditions was found to be 4.53 g per litre of the medium. Valine has been isolated in crystalline form from the fermented broth by ion exchange resin chromatography and found to be a pure sample of the L-isomer.

Bacillus subtilis↗
PubMed1977

Growth inhibition of Escherichia coli K-12 by L-valine: a consequence of a regulatory pattern.

We studied the production of the ilvG gene product, the valine resistant acetolactate synthase isoenzyme II, in an ilvO+ G+ ilvB ilvHI derivative of Escherichia coli K-12. This strain contains mutations in the structural genes for the valine sensitive acetolactate synthase isoenzymes I and III. We find that the ilvG gene is not expressed in this strain when gworn with either isoleucine and valine or with isoleucine, leucine and valine, or when limited for either isoleucine or valine. Since we previously found that the ilvG gene is expressed in an ilvO603 containing strain (Favre et al., 1976), we presume that the mechanism by which E. coli K-12 regulates the ilv gene cluster is responsible for the lack of ilvG expression in the ilvO+ strain. The valine sensitivity of E. Coli K-12 is a consequence of this regulatory pattern.

Acetolactate Synthase↗
PubMed1978

Carbon and nitrogen nutrition of Aerobacter aerogenes for valine production.

A number of carbon and nitrogen compounds were tested for their effect on growth of Aerobacter aerogenes and valine production. Sucrose was found to be the superior carbon source for valine production, while mannose supported maximum cellular growth with very poor yield of valine. Urea was found to be the adequate nitrogen source for valine production. Supplementation of the synthetic medium with complex nutrients lowered the yield of valine. No direct relationship between the growth of the organism and the formation of the amino acid was noticed. On the basis of this study, a suitable synthetic medium for valine production has been developed.

Carbon↗
PubMed1978

Suppressors of a genetic regulatory mutation affecting isoleucine-valine biosynthesis in Escherichia coli K-12.

Escherichia coli K-12 mutant PS187 carries a mutation, ilvA538, in the structural gene for the biosynthetic L-threonine deaminase that leads to a leucine-sensitive growth phenotype, an isoleucine- and leucine-hypersensitive L-threonine deaminase, and pleiotropic effects resulting in abnormally low and invariant expression of some of the isoleucine-valine biosynthetic enzymes. Fifty-eight derivatives of strain PS187 were isolated as resistant to growth inhibition by leucine, by valine, or by valine plus glycly-valine and were biochemically, genetically, and physiologically characterized. All of these derivatives produced the feedback-hypersensitive L-threonine deaminase, and thus presumably possess the ilvA538 allele of the parent strain. Elevated synthesis of L-threonine deaminase was observed in 41 of the 58 isolates. Among 18 strains analyzed genetically, only those with mutations linked to the ilv gene clusters at 83 min produced elevated levels of L-threonine deaminase. One of the strains, MSR91, isolated as resistant to valine plus glycyl-valine, was chosen for more detailed study. The locus in strain MSR91 conferring resistance was located in four factor crosses between ilvE and rbs, and is in or near the ilvO gene postulated to be a site controlling the expression of the ilvEDA genes. Synthesis of the ilvEDA gene products in strain MSR91 is constitutive and derepressed approximately 200-fold relative to the parent strain, indicating that the genetic regulatory effects of the ilvA538 allele have been suppressed. Strain MSR91 should be suitable for use in purification of the ilvA538 gene product, since enzyme synthesis is fully derepressed and the suppressor mutation is clearly not located within the ilvA gene.

Chromosome Mapping↗
PubMed1977

Effect of valine on propionate metabolism in control and hyperglycinemic fibroblasts and in rat liver.

Measurement of methylmalonyl-CoA mutase and propionyl-CoA carboxylase activities in lysates from fibroblasts derived from control, nonketotic hyperglycinemia, propionic acidemia, and both vitamin B12-responsive and -nonresponsive variants of methylmalonic acidemia showed only one abnormality: a 59% decrease in carboxylase activity in the nonketotic hyperglycinemic lysates (P less than 0.01). When fibroblasts from all cell types were grown on valine-supplemented (24 mM) media, mutase activity was generally inhibited. As for carboxylase activity, control lines were inhibited 35% as compared to controls without valine and propionic acidemia activity was undetectable. On the other hand, carboxylase activity in both methylmalonic acidemia variants was increased 40% and nonketotic hyperglycinemia carboxylase activity was increased 80% (P less than 0.01) when grown on valine-supplemented media. Isoleucine could not substitute for valine in producing increased carboxylase activity in these mutants. Glycine cleavage activity in fresh rat liver homogenates (11.1 micronmol/gm protein/90 min) did not vary significantly when 24 mM valine was added to the reaction (9.9 micronmol/mg protein/90 min). Therefore, the hyperglycinemia observed in both ketotic and nonketotic forms is probably not caused by a direct effect of valine on the glycine cleavage reaction. These data suggest that the presence of increased amounts of propionic acid in serum or urine does not necessarily rule out the possibility of nonketotic hyperglycinemia due to the decreased activity of the carboxylase enzyme.

Carboxy-Lyases↗