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At least 523 records · Page 29Linked to original sources
PubMed1983

Healing of biodegradable vascular prosthesis. Incorporation of 3H-valine into proteins in the subendothelial scar and host intima-media of rat aorta.

Heparin treated and aldehyde crosslinked rat aorta segments were implanted in infrarenal aorta of homologous rats. One year following aortic replacement, the subendothelial scar and the prosthetic remnants were excised. The scar and the host intima-media were incubated with 3H-valine for 4 h and extracted with 5 M guanidinium chloride--0.05 M dithiothreitol--0.1 M Tris--0.1% EDTANa2 at pH 7.5 prior (Extract 1) and following (Extract 2) hydrolysis of collagen. The radioactivity of extract 1 accounted for approximately 80% of the total label incorporated in the scar and host intima-media. The 3H-label of extract 1 adjusted for the tissue collagen content was about twenty times higher in the scar than in the host aorta. The major 3H protein peaks from Extract 1 of scar and host aorta were of 130 K, 100 K and 70 K apparent molecular weight, based on polyacrylamide gel electrophoresis in SDS. Hydrolysis with 2N KOH of the extraction residue from the host aorta and scar yielded 3H-val-pro dipeptides and hydrolysis with 6N HCl desmosines. The incorporation pattern of 3H-valine into proteins and the presence of elastin synthesized de novo in the scar replacing the prosthesis indicate macromolecular repair of the host aortic wall.

Animals↗
PubMed1989

Enkephalin regulation of L-valine transport in rabbit ileum.

We studied the influence on ionic basal transport (Na+ and Cl-) and L-valine transport of two enkephalins which are not metabolized and act in delta and mu receptors respectively. Transports have been indirectly determined measuring the transepithelial electric potential and the short circuit current. DADLE does not significantly influence ion and amino-acid transport, while DAGO alters both of them in the presence of the myenteric plexus (muscle layers present) or inhibits only L-valine transport in the absence of the plexus (muscle layers removed).

Animals↗
PubMed1977

Valine, leucine, and isoleucine metabolism by lactating bovine mammary tissue.

Valine, leucine, and isoleucine were extracted by the lactating bovine mammary gland in excess of outputs in milk protein. Carbon-14 uniformly labeled L-valine, L-leucine or L-isoleucine were catabolized when incubated in vitro with lactating bovine mammary tissue slices. The pathways of degradation of these amino acids by mammary tissue appear to be those common to other tissues. These amino acids represent a potential source of energy to the mammary gland as well as a source of carbon and alpha-amino nitrogen for synthesis of nonessential amino acids.

Acetates↗
PubMed2004

Valine influences production and complex composition of glycopeptide antibiotic A40926 in fermentations of Nonomuraea sp. ATCC 39727.

In actinomycetes the catabolism products of branched chain amino acids provide biosynthetic precursors for the formation of several lipid-containing antibiotics. We have determined in Nonomuraea sp. ATCC 39727 the effect of valine on production of glycopeptide antibiotic A40926, which is a complex of factors structurally differing in fatty acid moieties. Addition of valine to minimal medium increased A40926 production and modified complex composition towards a mono-component. Similar results were also obtained in a rich production medium.

Actinobacteria↗
PubMedDate not supplied

[Changes in the primary structure of rabbit muscle aldolase under the influence of valine against a background of prolonged fasting].

The primary structure of the muscle aldolase molecule was studied as affected by semilethal doses of valine administered the abdominal cavity of the rabbits after a long fasting. It is established that in spite of differences in the amino acid composition of the protein, uniformity of the peptides distribution in the process of bromo-cyanogen fragments elution and the total amount of amino acid residues in the identical fragments are maintained. Changes are found only in the point-replacements by amino acids in C-fragment of the molecule (asparagine is replaced by valine and threonine by serine).

Amino Acid Sequence↗
PubMed1999

[Utilization of glucose, valine, glycerin and palmitic acid by energy and anabolic pathways of metabolism in rats].

Possibility of evaluation of nutrients use by energy and anabolic ways by measurement in blood of radioactivity of water formed from labelled by tritium precursors was studied. The experiment was made on rats, which consecutively with interval 1.5-2 weeks were given intravenous indicative amount of 3H2(2,3)-valine, 1-14C-glucose, 6-3H-glucose, 3H2(1,3)-glycerin and 3H2(9,10)-palmitic acid. Half-time of glucose in blood was 46 min, glycerin--16 min, valine and palmitic acid--24 min. Plastic and energy characteristics of these substances were studied. The proposed approach to the evaluation of plastic and energy functions of nutrients can be useful for development of specialized products for enteral and parenteral feeding.

Animals↗
PubMed2000

Mutagenesis studies on the sensitivity of Escherichia coli acetohydroxyacid synthase II to herbicides and valine.

Acetohydroxyacid synthase (EC 4.1.3.18, also known as acetolactate synthase) isoenzyme II from Escherichia coli is inhibited by sulphonylurea and imidazolinone herbicides, although it is much less sensitive than the plant enzyme. This isoenzyme is also unusual in that it is not inhibited by valine. Mutating S100 (Ser(100) in one-letter amino acid notation) of the catalytic subunit to proline increases its sensitivity to sulphonylureas, but not to imidazolinones. Mutating P536 to serine, as found in the plant enzyme, had little effect on the properties of the enzyme. Mutating E14 of the regulatory subunit to glycine, either alone or in combination with the H29N (His(29)-->Asn) change, did not affect valine-sensitivity.

Acetolactate Synthase↗
PubMed2001

Pharmacological study on recombinant human GABA-A receptor complex containing alpha5 (leucine155 to valine) combined with beta3gamma2s subunits.

AIM: To investigate the characterization of the pharmacology of recombinant human GABA-A receptor complex containing alpha5beta3gamma2s subunits, and clarify which amino acids are essential for binding affinity. METHODS: We constructed chimeric subunit of alpha5 (leucine mutated to valine in 155) by site-directed mutation, combined alpha5 or alpha5 (valine 155) with beta3gamma2s subunits by using the baculovirus-transfected Sf-9 insect cell expressing system. Fifteen commercially available effective compounds for the GABA binding recognition site were determined. RESULTS: We found that competitive antagonist SR95531 and inhibitor Thio-4-piol increased IC50 values about 3 folds in alpha5 (valine155) beta3gamma2s compare to alpha5 (leucine155) beta3gamma2s receptor subunit combinations; Other GABA-A receptor ligands have little difference. CONCLUSION: The amino acid residues in 155 is important for the binding affinity and efficacy of SR95531 and Thio-4-piol to GABA-A receptor combinations containing an alpha5 subunit.

Animals↗
PubMed2002

Symbiotic characterization of isoleucine+valine and leucine auxotrophs of Sinorhizobium meliloti.

Ten isoleucine+valine and three leucine auxotrophs of Sinorhizobium meliloti Rmd201 were obtained by random mutagenesis with transposon Tn5 followed by screening of Tn5 derivatives on minimal medium supplemented with modified Holliday pools. Based on intermediate feeding, intermediate accumulation and cross-feeding studies, isoleucine+valine and leucine auxotrophs were designated as ilvB/ilvG, ilvC and ilvD, and leuC/leuD and leuB mutants, respectively. Symbiotic properties of all ilvD mutants with alfalfa plants were similar to those of the parental strain. The ilvB/ilvG and ilvC mutants were Nod-. Inoculation of alfalfa plants with ilvB/ilvG mutant did not result in root hair curling and infection thread formation. The ilvC mutants were capable of curling root hairs but did not induce infection thread formation. All leucine auxotrophs were Nod+ Fix-. Supplementation of leucine to the plant nutrient medium did not restore symbiotic effectiveness to the auxotrophs. Histological studies revealed that the nodules induced by the leucine auxotrophs did not develop fully like those induced by the parental strain. The nodules induced by leuB mutants were structurally more advanced than the leuC/leuD mutant induced nodules. These results indicate that ilvB/ilvG, ilvC and one or two leu genes of S. meliloti may have a role in symbiosis. The position of ilv genes on the chromosomal map of S. meliloti was found to be near ade-15 marker.

DNA Transposable Elements↗
PubMed2006

Identification of essential amino acid residues in valine dehydrogenase from Streptomyces albus.

Cys-29 and Cys-251 of Streptomyces albus valine dehydrogenase (ValDH) were highly conserved in the corresponding region of NAD(P)(+)-dependent amino acid dehydroganase sequences. To ascertain the functional role of these cysteine residues in S. albus ValDH, site-directed mutagenesis was performed to change each of the two residues to serine. Kinetic analyses of the enzymes mutated at Cys-29 and Cys-251 revealed that these residues are involved in catalysis. We also constructed mutant ValDH by substituting valine for leucine at 305 by site-directed mutagenesis. This residue was chosen, because it has been proposed to be important for substrate discrimination by phenylalanine dehydrogenase (PheDH) and leucine dehydrogenase (LeuDH). Kinetic analysis of the V305L mutant enzyme revealed that it is involved in the substrate binding site. However it displayed less activity than the wild type enzyme toward all aliphatic and aromatic amino acids tested.

Amino Acid Oxidoreductases↗
PubMed1991

Mucopolysaccharidosis VI (Maroteaux-Lamy syndrome). An intermediate clinical phenotype caused by substitution of valine for glycine at position 137 of arylsulfatase B.

The Maroteaux-Lamy syndrome (mucopolysaccharidosis type VI) is a lysosomal storage disease with autosomal recessive inheritance caused by deficiency of the enzyme arylsulfatase B. Severe, intermediate, and mild forms of the disease have been described. The molecular correlate of the clinical heterogeneity is not known at present. To identify the molecular defect in a patient with the intermediate form of the disease, arylsulfatase B mRNA from his fibroblasts was reverse-transcribed, amplified by the polymerase chain reaction, and subcloned. Three point mutations were detected by DNA sequence analysis, two of which, a silent A to G transition at nucleotide 1191 and a G to A transition at nucleotide 1126 resulting in a methionine for valine 376 substitution, were polymorphisms. A G to T transversion at nucleotide 410 causing a valine for glycine 137 substitution (G137V) was identified as the mutation underlying the Maroteaux-Lamy phenotype of the patient, who was homozygous for the allele. The kinetic parameters of the mutant arylsulfatase B enzyme toward a radiolabeled trisaccharide substrate were normal excluding an alteration of the active site. The G137V mutation did not affect the synthesis but severely reduced the stability of the arylsulfatase B precursor. While the wild type precursor is converted by limited proteolysis in late endosomes or lysosomes to a mature form, the majority of the mutant precursor was degraded presumably in a compartment proximal to the trans Golgi network and only a small amount escaped to the lysosomes accounting for the low residual enzyme activity in fibroblasts of a patient with the juvenile form of the disease.

Alleles↗
PubMed1990

Both valine and isoleucine supplementation delay the development of neurological impairment in vitamin B12 deficient bats.

Supplementation of the diet with valine or isoleucine protects the fruit bat from neurological impairment associated with experimentally induced vitamin B12 deficiency. Valine and isoleucine are precursors in the vitamin B12 dependent propionic acid pathway and it is proposed that they exert their protective effect through stimulation of this pathway. This suggests that the previously observed protective effect of methionine may be mediated also through this pathway, since methionine may be metabolised via the transsulfuration pathway to propionyl CoA. The results of this study refocus attention on the propionic acid pathway, and specifically on the methylmalonyl CoA mutase reaction, as central to the biochemical basis of the vitamin B12 neuropathy.

Animals↗
PubMed1979

Relative efficiency of anticodons in reading the valine codons during protein synthesis in vitro.

Using a protein synthesizing in vitro system programmed with MS 2-RNA, the relative efficiency (in the presence of each other) of valine tRNAs with the anticodons U*AC (U* represents 5-oxyacetic acid uridine monophosphate), GAC, and IAC to read the valine codons was investigated. An anticodon which can read all three positions of the codon according to the rules of Watson-Crick base-pairing and the wobble hypothesis is an order of magnitude more efficient than an anticodon which misreads the codon by reading only the first two positions and presumably disregards the third nucleotide of the codon. There are two seeming exceptions to this behavior: the anticodon U*AC reads the codon GUU quite efficiently and IAC is as effective as U*AC in reading the codon GUG. The significance of these exceptions is evaluated with respect to the organization and evolution of the genetic code.

Anticodon↗
PubMed1980

Incorporation of 3H-2,3-DL-valine into pancreatic proteins of adrenalectomized rats stimulated with pancreozymin-CCK and secretin.

Incorporation of labelled valine was investigated in bilaterally adrenalectomized rats stimulated with pancreozymin-CCK and secretin 14 days after operation. The growth of rats, the blood pressure, the amount of pancreatic juice and the amylase output was less in the adrenalectomized animals as compared with sham operated or adrenalectomized and corticosterone substituted controls. The amylase concentration in the pancreatic juice reveals no difference between the groups but the output of amylase remained below that of the controls. The incorporation of labelled valine was higher in the pancreatic tissue and proteins in the adrenalectomized animals than in the controls. It is assumed that the adrenalectomy causes primarily a depletion in the metabolic activity and systemic blood pressure; diminished pancreatic juice secretion and output of amylase are only secondary consequences which are not compensable by hormonal stimulation of pancreatic secretion.

Adrenalectomy↗
PubMed1983

General properties of 14C-L-Valine-binding to human brain tissue.

L-Valine (VAL) binding is saturable, reversible, linear within a protein concentration of 0.2 to 0.8 mg prot./ml, pH dependent (pH-optimum 7.1 to 7.4), temperature dependent with extremely low binding at 0-4 degrees C; the assay runs at 37 degrees C; it is ion dependent (Bmax:CaCl2 (5mM): + 100%; NaCl (5 mM): -50%); very sensitive to TRITON X-100 (Bmax at 0.01%; -70%); N-ethylmaleimide (0.5 mM): Competitive inhibition; no change in non-specific binding; there are no effects by puromycin plus GTP; VAL binds to synaptic membranes of human frontal cortex with KD-values several fold lower than that observed with homogenates, the distribution of VAL-binding is different in various human brain areas and can be inhibited by L-leucine, L-isoleucine, L-serine, DL-threonine, glycine and D-valine, while aromatic amino acids, beta-alanine, GABA, taurine, glutamate, proline and gamma-glutamyltaurine have no effects of 10(-3) M.

Aged↗
PubMed1981

The degree of conversion of alpha-keto acids to valine and phenylalanine in health and uraemia.

13C-labelled alpha-keto acid analogues of valine and phenylalanine were given by mouth and by intravenous route to three healthy and four uraemic individuals who were used as their own controls. The excretion of 13CO2 in expired air and of 13C-labelled keto acid in urine was measured together with plasma and, in some cases, intramuscular concentrations of total and 13C-labelled free valine and phenylalanine. A minimum and maximum limit of degree of conversion of these two alpha-keto acids to essential amino acids were calculated and was of the order of 25-50 per cent for both keto acids given by either route in health and uraemia.

Administration, Oral↗
PubMed1980

[Funtional study of gene relA in the expression of amino acid operons. III. The effect of the allelic state of gene relA on the derepression of the threonine and isoleucine-valine operons of Escherichia coli K-12].

During the derepression of threonine and isoleucine-valine operons the increase of activity of homoserine dehydrogenase and threonine deaminase respectively occurs only in relA+ strains of Escherichia coli K-12, while the activity of these enzymes in relA mutants does not change. The increase of the activity of homoserine dehydrogenase in relA+ strains corresponds to the increase of the fraction of the thr-mRNA, i.e. the expression of threonine operon is regulated at the level of transcription. After isoleucine is exhausted, only relA+ cells of threonine producer MG442 increase homoserine dehydrogenase activity and production of threonine. Thus, the regulation of transcription and translation of threonine and isoleucine-valine operons depends upon the allelic state of the relA gene.

Alleles↗
PubMed1982

beta-hydroxyisobutyryl coenzyme A deacylase deficiency: a defect in valine metabolism associated with physical malformations.

An infant, born to parents who were first cousins had multiple physical malformations. An associated biochemical abnormality was suggested by the urinary excretion of cysteine and cysteamine conjugates of methacrylic acid. The coenzyme A (CoA) ester of this compound is an intermediate in the pathway of valine oxidation. Subsequent investigation revealed a deficiency of beta-hydroxyisobutyryl-CoA deacylase, an enzyme unique to valine metabolism. The enzyme defect results in accumulation of methacrylyl-CoA, a highly reactive compound, which readily undergoes addition reactions with free sulfhydryl groups. Tissue damage due to reactions between methacrylyl-CoA and important sulfhydryl-containing enzymes and cofactors may account for the teratogenic effects seen in this patient.

Abnormalities, Multiple↗