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PubMedDate not supplied

[Effect of a space diet on valine concentrations in the blood].

The content of valine was measured in plasma of 6 healthy male test subjects who were either on a normal or Salyut-5 space diet for 30 days. The measurements were performed with the aid of a Hitachi KLA-3B amino acid analyzer. Unlike other studies, blood samples were withdrawn every 5 days. The results suggest that the postflight decrease of the valine content is associated with the food composition. This makes it necessary to improve the amino acid composition of space diets and the technology of their manufacture. The foodstuffs used in the recovery period should be supplemented with amino acids, particularly valine, to compensate for enhanced anabolic processes.

Adolescent↗
PubMed1978

[1-11C] DL-valine, a potential pancreas-imaging agent.

There is a great need for a better pancreas-imaging agent. Studies with [1-14C] DL-valine have shown this amino acid to have a high pancreatic specificity in the four animal species examined. The tissue distribution was almost optimal by 30 min after injection, and no carrier effect was observed through a dose of 5 mg/kg. [1-11C] DL-Valine was synthesized in amounts up to 363 mCi using a rapid (T1/2 = 20.4 min for C-11), high-temperature, high-pressure modification of the Bücherer-Strecker amino acid synthesis. Purification was by anion-exchange followed by cation-exchange chromatography. [1-11C] DL-Valine was obtained in a 70% chemical yield with a total synthesis and purification time of 45 min. Studies in animals have demonstrated that it is a potentially useful new agent for clinical pancreatic imaging.

Animals↗
PubMed1976

[Heterogeneity of L-valine pool in Actinomyces sp. 26-115 producing actinomycin C].

Free intracellular valine in Actinomyces sp. 26-115 producing actinomycin C its functionally heterogenous. There are at least 2 pools of free valine. One of them supplies valine for protein biosynthesis and the second for the antibiotic biosynthesis. The volume of the pools is estimated. Inadequate reaction of the pools to similar effects is indicative of differences in their properties. The pool participating in protein biosynthesis strives for preservation of its volume. The pool participating in the antibiotic biosynthesis is capable of enlarging its volume to various levels depending on the change in the volume of the common intracellular pool.

Actinomyces↗
PubMed1982

[Antagonism of the ammonia effect on serotonin receptors by L-valine].

Ammonia and valine influence the activity of serotonin receptors in membranes of frontal cortex taken from brain removed at postmortem: Ammonia reduces maximal binding capacity of serotonin receptors, and this effect can be antagonized by valine. This modulatory effect of valine seems to be efficient at a lower level in tissues of patients with hepatic coma. Branched chain amino acids may have efficient therapeutic effects in hepatic coma due firstly to effects on the blood brain barrier by a well known mechanism of action and secondly to molecular interaction at the synaptic membrane.

Aged↗
PubMed1994

Mutation of valine residue unique to alpha subunit of Gs abolishes activation.

We recently characterized a decapeptide sequence (residues 367-376) that is important for the membrane association of the activated alpha subunit of Gs. We report here that when this sequence is replaced by the cognate sequence of Gi1 alpha subunit, the chimeric protein (Gsis alpha) still interacts with the membrane but cannot be activated, regardless of the mode of activation. Construction of various chimeras demonstrates that the single replacement of valine 367 by threonine, the cognate residue of Gi1 alpha subunit, fully reproduces the loss of activation. Analysis of nucleotide interaction reveals that the mutant V367T Gs alpha protein poorly binds GDP or GTP. On the other hand, the conservative change of valine to isoleucine does not alter activation. Interestingly, members of the Gs and G12 classes have a valine and an isoleucine, respectively, at this position, whereas members of the Gi or Gq class contain a threonine residue. The evolutionary relationship between the different classes suggests that the presence of a hydrophobic or a hydrophilic residue is not fortuitous in these alpha subunits and might provide distinctive structural and/or functional properties.

Amino Acid Sequence↗
PubMedDate not supplied

Clinical consequences of disorders in the intermediate metabolism of branched chain amino acids (valine, leucine and isoleucine).

Assays of the amino acid levels in 5,888 newborns and 20 subjects ranging in age from 1 to 20 years, suspected of metabolic diseases, revealed a case of "maple syrup urine disease" caused by disorders in the intermediate metabolism of valine, whose serum and urinary concentrations were followed up from the first days of life. This patient also showed frequent episodes of hypoglycemia. An early treatment with polyvitamins, minerals and trace elements for 18 months resulted in the partial reactivation of the deficient enzymatic systems and the return to normal of the serum and urinary valine and glucose values. Administration of the same treatment to patients over one year of age, showing clinical and biochemical data characteristic to the same disease, was much less effective, thus supporting the conclusion that the vitamins and minerals could be useful in the "maple syrup urine disease" only if they were administered immediately after the disease onset. The correlation index between the serum and urinary valine levels before and after therapy was +0.976 and +0.994, respectively.

Adolescent↗
PubMed1993

[Valine and branched-chain amino acids in the treatment of hepatic encephalopathy].

We studied the effects of infusion of a liver adapted amino acid solution (Amino-Mel hepa: Group A) versus a liver adapted amino acid solution plus L-valine (Amino-Mel hepa + L-valine: Group B) in 30 patients with decompensated liver cirrhosis with coma. Each 15 patients were randomly allocated to the group A and B, respectively. Both regimens included the infusion of glucose and fat, further supplementation of vitamins and trace elements in addition to the amino acid solution. The results of this study show that in patients with advanced stage of hepatic coma a valine increased supply of branched chain amino acids neither influences the course of the disease nor the death rate. The prognosis of patients with this disease is mainly determined by liver function and accompanying complications.

Amino Acids, Branched-Chain↗
PubMed1985

Identification and synthesis of [1-asparagine, 5-valine, 9-glycine] angiotensin I produced from plasma of American eel Anguilla rostrata.

The major peptide produced by incubation of American eel (Anguilla rostrata) plasma with the eel kidney extract was identified as [1-asparagine, 5-valine, 9-glycine] angiotensin I (I). Two minor peptides were also identified as [1-aspartic acid, 5-valine, 9-glycine] angiotensin I (II) and [5-valine, 9-glycine] angiotensin I-(3-10)-octapeptide (III). These structures were further confirmed by comparison of these peptides on high-pressure liquid chromatography (HPLC) and high-performance thin-layer chromatography (HPTLC) with the synthetic peptides and the tryptic and chymotryptic digests of the synthetic and natural angiotensins. In the rat pressor bioassays, the synthetic decapeptides I and II possessed 45.4 and 52.2%, respectively, of the pressor activity of [1-aspartic acid, 5-isoleucine] angiotensin II. The pressor activity of I and II was blocked with the converting enzyme inhibitor captopril. Study of the conversion of asparaginyl decapeptide into aspartyl decapeptide in eel plasma indicated that the presence of thimerosal (sodium ethylmercurithiosalicylate) in the incubation mixture inhibited the conversion of I into II. These results suggest that (a) I is the natural form of angiotensin inherent in the American eel while II may be formed during incubation with plasma; (b) eel plasma contains an enzyme which is capable of converting asparaginyl angiotensins into aspartyl angiotensins; and (c) pressor activity of I and II is due to their conversion into the corresponding octapeptides. In a previous work when thimerosal was not included in the incubation mixture, the major peptide produced by incubation of Japanese eel (Anguilla japonica) plasma with its kidney extract was identified as II. (Y. Hasegawa, T. Nakajima, and H. Sokabe, 1983, Biomed. Res. 4, 417-420).

Angiotensin I↗
PubMed1997

Penicillin biosynthesis: intermediates of biosynthesis of delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine formed by ACV synthetase from Acremonium chrysogenum.

The tripeptide delta-L-alpha-aminoadipyl-L-cysteinyl-D-valine (LLD-ACV) is synthesised by the multifunctional enzyme ACV synthetase integrating four steps of the penicillin and cephalosporin biosynthetic pathway. Peptide synthesis follows the thiotemplate mechanism from intermediates bound as thioesters to the enzyme. The formation of delta-(L-alpha-aminoadipyl)-L-cysteinyl-thioester in the absence of L-valine was shown by isolation of the enzyme-substrate complex and cleavage of the covalently bound intermediate with performic acid. The dipeptide was recovered as cysteic acid or cysteic acid oxime and detected by HPLC and MALDI-TOF mass spectrometry. We conclude that the first peptide bond is formed between delta-carboxyl of L-aminoadipic acid and L-cysteine, followed by addition of the dipeptidyl intermediate to L-valine.

Acremonium↗
PubMed1980

Thermodynamic studies of binding proteins: effects of temperature variations on substrate binding and conformation of the leucine-isoleucine-valine binding protein of Escherichia coli.

The behaviour of the Leucine isoleucine Valine binding protein of Escherichia coli as a function of temperature has been examined. Substrate binding measurements showed a temperature dependence of the leucine-isoleucine-valine binding protein leucine complex formation constants. The protein-substrate complex was completely dissociated beyond 70 degrees C. In the range 5-65 degrees C the protein remained active but Van't Hoff's plots indicated changes of the reaction thermodynamic parameters. Large negative delta Cp values (--2.25 kJ mole-1 K-1 between 5 and 40 degrees C and--9.40 above 40 degrees C) indicate important substrate induced modifications of the protein conformation. Scanning calorimetry of the leucine isoleucine valine binding protein before and after addition of leucine was also performed. Two thermal events were recorded when the protein was substratefree and only one, at a higher temperature and more important, when the substrate was added. The results of these two approaches were in agreement in that both methods suggested a binding dependent conformational change of the protein which resulted in a greater stability of its structure.

Bacterial Proteins↗
PubMed1984

Potent and selective antagonists of the antidiuretic responses to arginine-vasopressin based on modifications of [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-isoleucine,4- valine]arginine-vasopressin at position 4.

As part of a program in which we are attempting (a) to obtain more potent and/or more selective antagonists of the antidiuretic responses to arginine-vasopressin (AVP) and (b) to delineate the structural features at positions 1-9 required for antidiuretic antagonism, we have synthesized 13 new analogues of the antidiuretic antagonist [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-isoleucine,4- valine]arginine-vasopressin [d(CH2)5[D-Ile2]VAVP] in which the valine residue at position 4 has been replaced by the L-amino acids Abu, Ile, Thr, Ala, Ser, Nva, Gln, Leu, Lys, Cha, Asn, Orn, and Phe and two new analogues of the antidiuretic antagonist [1-(beta-mercapto-beta,beta-pentamethylenepropionic acid),2-D-phenylalanine,4- valine]arginine-vasopressin [d(CH2)5[D-Phe2]VAVP] with the Val4 residue replaced by Ser and Orn. These analogues are 1, d(CH2)5[D-Ile2,Abu4]AVP; 2, d(CH2)5[D-Ile2,Ile4]AVP; 3, d(CH2)5[D-Ile2,Thr4]AVP; 4, d(CH2)5[D-Ile2,Ala4]AVP; 5, d(CH2)5[D-Ile2,Ser4]AVP; 6, d(CH2)5[D-Ile2,Nva4]AVP; 7, d(CH2)5[D-Ile2]AVP; 8, d(CH2)5[D-Ile2,Leu4]AVP; 9, d(CH2)5[D-Ile2,Lys4]AVP; 10, d(CH2)5[D-Ile2,Cha4]AVP; 11, d(CH2)5[D-Ile2,Asn4]AVP; 12, d(CH2)5[D-Ile2,Orn4]AVP; 13, d(CH2)5[D-Ile2,Phe4]AVP; 14, d(CH2)5[D-Phe2,Ser4]AVP; and 15, d(CH2)5[D-Phe2,Orn4]AVP. The protected peptide precursors for these peptides were prepared by the solid-phase method, followed by ammonolytic cleavage. The free peptides 1-15 were obtained by deblocking with Na in NH3, oxidation of the resultant disulfhydryl compounds with dilute K3[Fe(CN)6], and purification on Sephadex G-15 in a two-step procedure with 50% HOAc and 0.2 M HOAc as eluants. Analogues 1-15 were tested in rats for agonistic and antagonistic activities by antidiuretic, vasopressor, and oxytocic assays.(ABSTRACT TRUNCATED AT 250 WORDS)

Animals↗
PubMed1999

Symmetry, pseudosymmetry and packing disorder in the alcohol solvates of L-leucyl-L-valine.

The dipeptide L-Leu-L-Val can crystallize as a hydrate in the hexagonal space group P6(5) [Görbitz & Gundersen (1996). Acta Chem. Scand. 50, 537-543], but forms 1:1 solvates when methanol, ethanol and 2-propanol are used as precipitating agents. The structures of these complexes can be divided into hydrophobic and hydrophilic layers. The alcohol molecules are embedded in the hydrophobic layers, but with the hydroxyl groups as crucial parts of the hydrogen-bonding network. L-Leucyl-L-valine-methanol (1/1) crystallizes in the space group P2(1) with Z = 2. L-Leucyl-L-valine-ethanol (1/1) has very special systematic absences, and the structure could not be solved with direct methods. Unraveling the actual build-up of the crystal was an unusual process involving modeling with molecular graphics programs. The solution shows a structure which formally belongs to the space group P2(1), with four dipeptide molecules and four solvent molecules in the asymmetric unit (Z = 8). Additional non-crystallographic symmetry in three dimensions fixes all cell angles, including beta, to 90 degrees. L-Leucyl-L-valine-2-propanol (1/1) is structurally closely related to the ethanol solvate, but owing to a rare type of packing disorder the length of the a axis is halved (Z = 4, P2(1)2(1)2(1)). The hydrogen-bonding pattern is still the same as in the ethanol solvate, which means that the hydrogen-bond periodicity along the a axis in the 2-propanol solvate is two unit-cell lengths.

Journal Article↗
PubMed1983

Exogenous Valine Reduces Conversion of Leucine to 3-Methyl-1-Butanol in Saccharomyces cerevisiae.

Mutant strains of the yeast Saccharomyces cerevisiae that require branched-chain amino acids must be supplemented with large concentrations (up to 10 mM) of these amino acids to satisfy their nutritional requirement. The utilization of one branched-chain amino acid, leucine, was examined in several leul strains of yeast grown aerobically in a glucose-ammonium salts minimal medium containing a limiting concentration (0.2 mM) of leucine. In this medium, the leucine requirement of the auxotrophic strains could be reduced by valine, another branched-chain amino acid. Increasing the valine concentration increased the cell yields of cultures and also reduced the levels of 3-methyl-1-butanol detected in the medium by gas chromatography. The concentration of 3-methyl-1-butanol was reduced from 122.0 to 48.9 muM when 5.0 mM valine was supplemented to limiting-leucine cultures. The amino acids isoleucine, threonine, norleucine, norvaline, alpha-amino-butyrate, alanine, and glycine also spared the leucine requirement of leucine auxotrophs, most likely because they resembled leucine and competed for its uptake. We propose that leucine analogs restrict the entry and degradation of leucine and thus reduce its conversion to 3-methyl-1-butanol, a major component of fusel oil.

Journal Article↗
PubMed1988

Isolation and characterization of valine dehydrogenase from Streptomyces aureofaciens.

Valine dehydrogenase was purified to homogeneity from the crude extracts of Streptomyces aureofaciens. The molecular weight of the native enzyme was 116,000 by equilibrium ultracentrifugation and 118,000 by size exclusion high-performance liquid chromatography. The enzyme was composed of four subunits with molecular weights of 29,000. The isoelectric point was 5.1. The enzyme required NAD+ as a cofactor, which could not be replaced by NADP+. Sulfhydryl reagents inhibited the enzyme activity. The pH optimum was 10.7 for oxidative deamination of L-valine and 9.0 for reductive amination of alpha-ketoisovalerate. The Michaelis constants were 2.5 mM for L-valine and 0.10 mM for NAD+. For reductive amination the Km values were 1.25 mM for alpha-ketoisovalerate, 0.023 mM for NADH, and 18.2 mM for NH4Cl.

Amino Acid Oxidoreductases↗
PubMed1973

Hemoglobin olympia ( 20 valine leads to methionine): an electrophoretically silent variant associated with high oxygen affinity and erythrocytosis.

In a family with erythrocytosis, electrophoretic and chromatographic studies failed to demonstrate a hemoglobin variant. However, the oxygen dissociation curves of affected individuals were shifted to the left of normal and this shift persisted when oxygen equilibria were studied in 2.3-diphosphoglycerate-stripped hemolysates. A mutant hemoglobin was evidently present in the red blood cells of the affected persons and was responsible for the increased oxygen affinity and erythrocytosis. Specific staining of tryptic peptide maps of beta-chains from the propositus showed that peptide betaT(3) was positive for a sulfur-containing amino acid. Amino acid analysis yielded a composition identical to that of normal betaT(3), except that there were 2.6 residues of valine and 0.4 residues of methionine (normal composition: Val = 3.0, Met = 0). This suggested that the beta-chains of affected individuals consisted of a mixture of two kinds of chains, 40% of which had a methionyl residue in betaT(3). Structural studies of isolated cyanogen bromide fragments demonstrated unequivocally that, in the abnormal beta-chains, valine in position 20 is replaced by methionine. The new hemoglobin mutant is designated hemoglobin Olympia (beta20 (B2) valine --> methionine).

Adult↗
PubMed1989

A biologically active insulin analogue with modification in the A2 position. [2-Valine-A] sheep insulin.

The synthesis and biological evaluation of [2-Valine-A] insulin ([Val2-A]insulin) is reported. In this insulin, the isoleucine residue in position A2, invariant in the majority of mammalian insulins, is substituted by valine. The same substitution, along with four others, occurs naturally in the insulin produced by the owl monkey. Owl monkey insulin exhibits ca. 20% of the activity of porcine insulin in in vitro insulin assays using human cells in culture. [Val2-A]insulin displays 20-22% of the activity of bovine insulin in in vitro insulin assays using rat liver plasma membranes or isolated rat adipocytes. We suggest that the substitution of valine for isoleucine at position A2 is responsible for all or most of the diminution in potency of owl monkey insulin relative to porcine insulin. The data are discussed with regard to previous findings with insulin analogues in which isoleucine A2 was replaced with norleucine, glycine and alanine.

Amino Acids↗
PubMed2000

Alpha-aminoadipyl-cysteinyl-valine synthetases in beta-lactam producing organisms. From Abraham's discoveries to novel concepts of non-ribosomal peptide synthesis.

The tripeptide delta-(L-alpha-aminoadipyl)-L-cysteinyl-D-valine (ACV) was discovered by ARNSTEIN and MORRIS in Penicillium chrysogenum and ABRAHAM and coworkers in Acremonium chrysogenum. Other analogous tripeptides and tetrapeptides were later reported in these and other beta-lactam producing fungi and actinomycetes. The ACV tripeptide is synthesized by a large non-ribosomal peptide synthetase named ACV synthetase encoded by the 11 kb pchAB gene. This gene has been cloned from the DNA of four different filamentous fungi and two actinomycetes. Detailed analysis of the multifunctional ACV synthetases reveals that they consist of three repeated modules (initially named domains) involved in activation of the corresponding amino acids L-alpha-aminoadipic acid, L-cysteine and L-valine. Each module consists of functional domains for amino acid activation (A), condensation (C) and thiolation (T). In addition the last module of the ACV synthetase contains an epimerization domain (E) involved in conversion of the L-valine to its D-isomer when the tripeptide is still enzyme linked. There are seven epimerization motifs conserved in the third module of all ACV synthetases. In addition, there is an integrated thioesterase domain in the C-terminal region of the ACV synthetases that appears to be involved in the selective release of the tripeptide with the correct LLD configuration. The structure of the ACV synthetase is similar to that of other modular non-ribosomal peptide synthetases of bacterial and fungal origin. This molecular knowledge opens the way for engineering novel tripeptide synthetases that may result in new bioactive compounds.

Actinomycetales↗
PubMed1991

Anticodon-dependent aminoacylation of a noncognate tRNA with isoleucine, valine, and phenylalanine in vivo.

An assay based on the initiation of protein synthesis in Escherichia coli has been used to explore the role of the anticodon in tRNA identity in vivo. Mutations were introduced into the initiator tRNA to change the wild-type anticodon from CAU (methionine) to GAU (isoleucine), GAC (valine), and GAA (phenylalanine), where each derivative differs from the preceding by a single base change in the anticodon (underlined). These changes were sufficient to cause the mutant tRNAs to be aminoacylated by the corresponding aminoacyl-tRNA synthetases based on the amino acid inserted into protein from complementary initiation codons. Construction of additional single base anticodon variants (GUU, GGU, GCC, GUC, GCA, and UAA) showed that all three anticodon bases specify isoleucine and phenylalanine identity and that both the middle and the third anticodon bases are important for valine identity in vivo.

Amino Acyl-tRNA Synthetases↗