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PubMed2000

[The spectra and thermodynamics of axial coordination reaction of tailed valine tetraphenylporphintozinc with pyrimidine].

The electronic absorption spectra and thermodynamics of axial coordination reaction of 5-(4-valine butoxyphenyl)-10,15,20-tri(4-chlorophenyl)porphintozinc with pyrimidine in CHCl3 were studied. Coordination numbers and equilibrium constants of axial coordination reaction were measured by visible spectra techniques. The changes of standard molar enthalpies and standard molar entropies of reaction were obtained from the plots of ln beta vs 1/T. The influence of temperature on the axial reaction was discussed.

Porphyrins↗
PubMed1992

Hemoglobin Thionville. An alpha-chain variant with a substitution of a glutamate for valine at NA-1 and having an acetylated methionine NH2 terminus.

In hemoglobin (Hb) Thionville, the substitution of a glutamic acid for the alpha-chain NH2-terminal valine inhibits the cleavage of the initiator methionine which is then acetylated. The elongation of the alpha-chain NH2 terminus modifies the three-dimensional structure of hemoglobin at a region that is known to have an important role in the allosteric regulation of oxygen binding. Relative to Hb A, Hb Thionville has a lower affinity for oxygen, and the heterotropic allosteric effects of protons, chloride, and bezafibrate are reduced. In contrast, the response to 2,3-diphosphoglycerate is normal. Analysis of oxygen equilibrium data within the framework of the two-state allosteric model indicates that the structure of deoxy Hb Thionville is stabilized relative to that of deoxy Hb A. The x-ray crystal structure of deoxy Hb Thionville shows that the glutamate side chain extends away from the alpha 1-alpha 2 interface, whereas the methionine side chain (which has two conformations) extends into the alpha 1-alpha 2 interface, physically displacing chloride and bezafibrate. The increased stability of deoxy Hb Thionville is due to new intrasubunit and intersubunit contacts made by the methionine. These interactions replace the indirect contacts, made through bound chloride ions, that Val-1 alpha normally contributes to the alpha 1-alpha 2 interface.

Acetylation↗
PubMed1992

Molecular dosimetry of ethylene oxide: formation and persistence of N-(2-hydroxyethyl)valine in hemoglobin following repeated exposures of rats and mice.

The formation of N-(2-hydroxyethyl)valine (HEVal) in hemoglobin was investigated in male F344 rats (10/group) and B6C3F1 mice (20/group) exposed to 0, 3, 10, 33, 100, or 300 (rats only) ppm ethylene oxide (ETO) by inhalation for 6 h/day for 4 weeks (5 days/week) or exposed to 100 (mice) or 300 ppm (rats) ETO for 1 or 3 days, or 1, 2, or 4 weeks (5 days/week). The persistence of HEVal was studied in animals killed up to 10 days after cessation of the 4-week time-course studies. HEVal was determined by a modified Edman degradation and quantitation of the resulting pentafluorophenylthiohydantoin derivative, using gas chromatography-mass spectrometry. The resulting experimental data were compared to simulations derived with a model for the formation and removal of hemoglobin adducts (T.R. Fennell, S.C.J. Sumner, and V.E. Walker, Cancer Epidemiol., Biomarkers & Prev., 1: 213-219, 1992). Repeated exposures of rats and mice for 4 weeks to 300 and 100 ppm ETO, respectively, led to an accumulation of HEVal that was 14 (rats) and 15 (mice) times greater than that found after 1 day of exposure [28 +/- 2 (SE) and 9.4 +/- 0.4 (SE) pmol HEVal/mg globin in rats and mice, respectively]. After cessation of exposures, HEVal was lost faster than predicted by the normal erythrocyte life span alone. An initial phase of rapid decline in HEVal concentrations was consistent with the removal of older, more heavily alkylated populations of RBCs, accompanied by a burst of erythropoiesis. The dose-response curves for HEVal were linear between 3 and 33 ppm ETO, with 3.5 +/- 0.2 and 3.4 +/- 0.3 pmol adduct/mg globin formed in rats and mice, respectively, after 4 weeks of exposure to 3 ppm ETO. Above 33 ppm ETO, the slope of the dose-response curves increased. Comparison of the dose response for HEVal in rats exposed to ETO for 4 weeks to the dose-response for N tau-(2-hydroxyethyl)histidine in rats exposed to the same concentrations of ETO for 2 years (S. Osterman-Golkar et al., Teratog. Carcinog. Mutagen., 3: 395-405, 1983) suggested that exposures to ETO can reduce the life span of erythrocytes in a concentration- and time-dependent manner. Correlation of the experimental data and simulations for the formation and removal of HEVal demonstrated that perturbations in erythropoiesis and RBC life span complicate the estimation of exposures to ETO when estimates are based upon hemoglobin adduct measurements in heavily exposed individuals.(ABSTRACT TRUNCATED AT 400 WORDS)

Administration, Inhalation↗
PubMed1992

Germ-line mosaicism for a valine-to-methionine substitution at residue 553 in the glycoprotein Ib-binding domain of von Willebrand factor, causing type IIB von Willebrand disease.

The origin of new single-gene mutations resulting in inherited disease is an issue which may be at least partially resolved by our enhanced ability to detect these changes. In this report we describe the identification of a missense mutation at codon 553 (guanine to adenine) in the von Willebrand factor (vWf) gene in affected members of a family with type IIB von Willebrand's disease (vWd). We found no evidence for this substitution in 190 normal vWf genes. The encoded substitution of a methionine for a valine at this residue is nonconservative in nature and has affected a vWf protein region which has been shown to facilitate binding to the platelet receptor glycoprotein Ib. In patients with type IIB vWd this interaction is characteristically increased in affinity. This mutation has also recently been recorded in four other type IIB vWd families. Thus, there is strong circumstantial evidence to incriminate this substitution as the disease causing mutation in this family. As further supporting evidence for this claim, we have shown by vWf polymorphism analysis that the mutation originated in a vWf gene transmitted from a phenotypically normal grandfather. Analysis of the sperm from this individual showed that approximately 5% of the germ line contained the mutant 553 sequence. These results confirm (1) that the candidate type IIB vWd mutation in this family occurred at some time during the development of the germ line of the grandfather and presumably was related to a mitotic cell division and (2) that, as a result, he is a low-level germ-line mosaic for the mutation.

Autoradiography↗
PubMedDate not supplied

[Valine substitution].

The review deals with analysis of the literature data concerning the importance of valine substitution in certain proteins, namely p21 ras and hemoglobin. A model of the active site of p21 protein is discussed in the light of GTPase activities alterations as a result of monoaminoacid substitution in conservative sites of p21 protein. The established relationship between some forms of transformation and Plasmodium falciparum malaria on the molecular level is shown in a new aspect. The widespread opinion that Hb S is valid as the means of malaria resistance is questioned in terms of new molecular data.

Amino Acid Sequence↗
PubMed1975

Solubilization of valine-sensitive acetohydroxy acid synthetase from Neurospora mitochondria.

Acetohydroxy acid synthetase [EC 4.1.3.18] of Neurospora crassa has been solubilized from a mitochondrial pellet fraction by sonic treatment in 1.0 M potassium phosphate buffer at pH 7.5 containing 10 mM MgSO4 and centrifugation at 180,000 X g for 20 min. The soluble enzyme thus obtained has a high specific activity and a high sensitivity to valine comparable to the original mitochondrial pellet suspension when the activity was determined in high concentrations of potassium phosphate.

Acetolactate Synthase↗
PubMed1989

Studies on methylmalonic acid in humans. I. Concentrations in serum and urinary excretion in normal subjects after feeding and during fasting, and after loading with protein, fat, sugar, isoleucine, and valine.

Determination of methylmalonic acid (MMA) in serum or urine for evaluation of tissue cobalamin (vitamin B12) deficiency is becoming an important diagnostic procedure. Here I present the first investigation of dietary influence on concentrations of MMA in serum and urine. Everyday meals caused an increase in urinary excretion, whereas the concentration in serum was not increased significantly. It is difficult to prime the accumulation of MMA in normal subjects by stressing the metabolic pathway; after loading subjects with 100 mmol of isoleucine or valine, the absolute amount of MMA excreted increased by only about 3 mumol. Its concentration in serum tended to decrease and its urinary excretion declined after lack of protein intake for more than 15 h. Although a linear relationship was demonstrated, for the first time, between concentrations in serum and urinary excretion, my results indicate that patients with early evidence of cobalamin deficiency and normal subjects may best be differentiated by measurements in serum, especially in the case of nonfasting (i.e., ambulatory) patients.

Adult↗
PubMed1989

A high proportion of ADA point mutations associated with a specific alanine-to-valine substitution.

In 15%-20% of children with severe combined immunodeficiency (SCID), the underlying defect is adenosine deaminase (ADA) deficiency. The overall goal of our research has been to identify the precise molecular defects in patients with ADA-deficient SCID. In this study, we focused on a patient whom we found to have normal sized ADA mRNA by Northern analysis and an intact ADA structural gene by Southern analysis. By cloning and sequencing this patient's ADA cDNA, we found a C-to-T point mutation in exon 11. This resulted in the amino acid substitution of a valine for an alanine at position 329 of the ADA protein. Sequence analysis revealed that this mutation created a new BalI restriction site. Using Southern analyses, we were able to directly screen individuals to determine the frequency of this mutation. By combining data on eight families followed at our institution with data on five other families reported in the literature, we established that five of 13 patients (seven of 22 alleles) with known or suspected point mutations have this defect. This mutation was found to be associated with three different ADA haplotypes. This argues against a founder effect and suggests that the mutation is very old. In summary, a conservative amino acid substitution is found in a high proportion of patients with ADA deficiency; this can easily be detected by Southern analysis.

Adenosine Deaminase↗
PubMed1977

Isolation and characterization of valine transfer RNA from Saccharomyces cerevisiae.

Two procedures for isolating valine tRNA from commercial bakers' yeast were investigated. The first involved: (a) counter double current distribution; (b) chromatography on benzoyl-DEAE-cellulose; (c) reverse phase chromatography on Chromosorb G saturated with trioctylpropylammonium bromide (Oakridge System 3). The material isolated lacked the 3'-terminal adenylic acid residue. The second procedure involved the first two steps above followed by: (a) enzymatic aminoacylation with a partially purified yeast extract; (b) derivatization with N-phenoxyacetoxysuccinimide; (c) chromatography on benzoyl-DEAE-cellulose; (d) reverse phase chromatography, System 3. The product was intact tRNA. It was a mixture of isoacceptors (59:41) differing by a modification (uracil leads to dihydrouracil) at position 48. It was free of denatured material; specific activity 1,825 pmol of valine/A260 unit of tRNA. Sequence analysis confirmed the recently corrected structure (Bonnet, J., Ebel, J. P., Dirheimer, G., Shershneva, L. P., Krutilina, A. I., Venkstern, T. V., and Bayev, A. A. (1974) Biochimie 56, 1211-1213). A preliminary study of the alkaline hydrolysis of the 7-methylguanosine residue that occurs at position 47 showed that at least two products are formed instead of only one as usually quoted in the literature. A rapid, ultramicro, chromatographic system for separating these products and measuring them quantitatively is described.

Guanosine↗
PubMed1979

Physiological characterization of polar Tn5-induced isoleucine-valine auxotrophs in Escherichia coli K.12: evidence for an internal promoter in the ilvOGEDA operon.

The properties of 22 isoleucine-valine auxotrophs induced in Escherichia coli K-12 by the transposable element, Tn5, were characterized on the basis of growth requirements, cross-feeding behavior, and enzyme activity. Mutants defective in ilvA, ilvC, ilvD and ilvE were found. Mutation in ilvE were not completely polar on ilvD and ilvA enzyme activities (that is, ilvE mutants possessed a low constitutive level of expression of the enzymes coded by ilvD and ilvA), while mutations in ilvD were completely polar on ilvA enzyme activity. The data suggest that there is an internal promoter between the sites of Tn5 insertion in ilvE and ilvD.

DNA Transposable Elements↗
PubMedDate not supplied

[Amino acid composition of preparations acid-soluble skin collagen and free amino acids in rat serum under loading with valine and methionine].

The valine and methionine loading against a background of protein-free diet evokes interrelated changes in amino acid composition of acid-soluble skin collagen preparations and free amino acids pool of blood serum in rats. The isolated collagen preparations also differ essentially from the normal preparations in the content of disulphide groups and elution profiles.

Amino Acids↗
PubMed1993

Antibodies to the extracellular receptor domain restore the hormone-insensitive kinase and conformation of the mutant insulin receptor valine 382.

A mutation substituting a valine for phenylalanine at residue 382 in the insulin receptor alpha-subunit has been found in two sisters with a genetic form of extreme insulin resistance. This receptor mutation impairs the ability of the hormone to activate autophosphorylation of solubilized receptors and phosphorylation of substrates (Accili, D., Mosthaf, L., Ullrich, A., and Taylor, S. I. (1991) J. Biol. Chem. 266, 434-439). We have previously demonstrated that in native receptors insulin induces a conformational change in the receptor beta-subunit, which is thought to be necessary for receptor activation (Baron, V., Gautier, N., Komoriya, A., Hainaut, P., Scimeca, J. C., Mervic, M., Lavielle, S., Dolais-Kitabgi, J., and Van Obberghen, E. (1990) Biochemistry 29, 4634-4641). Hence, it was thought that a defect in this conformational change might explain the functional defect of the mutant receptor. This appears to be the case, as we demonstrate here that the mutant receptor is locked in its inactive configuration. However, we found two monoclonal antibodies, directed to the extracellular domain, which are capable of restoring the mutant receptor kinase activity. The activation of the mutant receptor was accompanied by restoration of conformational changes in the beta-subunit C terminus. From these data, we draw the two following conclusions. (i) A causal link exists between receptor kinase activation and the occurrence of conformational changes. (ii) Ligands other than insulin, such as antibodies, which perturb the extracellular domain, can function as alternative ways to restore the mutant receptor kinase.

3T3 Cells↗
PubMed1997

Decreased agonist sensitivity of human GABA(A) receptors by an amino acid variant, isoleucine to valine, in the alpha1 subunit.

Recombinant human GABA(A) receptors were investigated in vitro by coexpression of cDNAs coding for alpha1, beta2, and gamma2 subunits in the baculovirus/Sf-9 insect cell system. We report that a single amino acid exchange (isoleucine 121 to valine 121) in the N-terminal, extracellular part of the alpha1 subunit induces a marked decrease in agonist GABA(A) receptor ligand sensitivity. The potency of muscimol and GABA to inhibit the binding of the GABA(A) receptor antagonist [3H]SR 95531 (2-(3-carboxypropyl)-3-amino-6-(4-methoxyphenyl)pyridazinium bromide) was higher in receptor complexes of alpha1(ile 121) beta2gamma2 than in those of alpha1(val 121) beta2gamma2 (IC50 values were 32-fold and 26-fold lower for muscimol and GABA, respectively). The apparent affinity of the GABA(A) receptor antagonist bicuculline methiodide to inhibit the binding of [3H]SR 95531 did not differ between the two receptor complex variants. Electrophysiological measurements of GABA induced whole-cell Cl- currents showed a ten-fold decrease in the GABA(A) receptor sensitivity of alpha1 (val 121) beta2gamma2 as compared to alpha1(ile 121) beta2gamma2 receptor complexes. Thus, a relatively small change in the primary structure of the alpha1 subunit leads to a decrease selective for GABA(A) receptor sensitivity to agonist ligands, since no changes were observed in a GABA(A) receptor antagonist affinity and benzodiazepine receptor binding.

Baculoviridae↗
PubMed1997

Rigidification of the alpha2 helix of an MHC class I molecule by a valine to proline mutation in position 165 does not prevent peptide-specific antigen presentation.

Although classical MHC class I glycoproteins bind peptide Ags for display at the cell surface, some MHC class I-related molecules such as the neonatal Fc receptor (FcRn) execute their function without binding peptide ligands. The three-dimensional structure of the FcRn suggested that a substitution of the conserved valine at position 165 of the alpha2 helix by proline contributed to a kink in the position of this helix relative to the alpha1 helix, and resulted in closing of the potential peptide-binding cleft. To test the contribution of proline 165 to the occlusion of the cleft and the binding of potential antigenic peptides, we introduced this mutation into the classical murine MHC class I molecule, H-2Dd, and characterized the ability of such a mutant to present peptide Ags to either a peptide-specific, H-2Dd-restricted T cell hybridoma (B4.2.3), or an allospecific, peptide-dependent, T cell hybridoma (3DT52.5.8). We show that the V165P mutation, expressed at the cell surface either in H-2Dd or in a single chain membrane version of H-2Dd, fails to eliminate recognition of the peptide/MHC complexes by two different T cells. Evaluation of a panel of synthetic substituted peptides suggests that subtle differences in the fine specificity of presentation can be discerned. Thus, the proline substitution at position 165 of FcRn and some other class I-like molecules is not the sole cause of the lack of peptide presentation.

Animals↗
PubMed1997

Dielectric relaxation study of glycine and valine in water mixture using picosecond time domain reflectometry.

The complex permittivity of glycine and valine in water mixture for various temperatures and concentrations have been measured as a function of frequency between 10 MHz and 10 GHz using (TDR) time domain reflectometry technique. Dielectric parameters ie. static dielectric constant and relaxation time were obtained from the complex permittivity spectra using nonlinear least square fit method. From the values of relaxation time, thermodynamic parameters were determined.

Electrochemistry↗
PubMed2004

Raman study of poly(alanine-glycine)-based peptides containing tyrosine, valine, and serine as model for the semicrystalline domains of Bombyx mori silk fibroin.

For a deeper insight into the structure of Bombyx mori silk fibroin, some model peptides containing tyrosine (Y), valine (V), and serine (S) in the basic (AG)n sequence were synthesized by the solid-phase method and analyzed by Raman spectroscopy in order to clarify their conformation and to evaluate the formation and/or disruption of the ordered structure typical of B. mori silk fibroin upon incorporation of Y, V, and S residues into the basic (AG)n sequence. The Raman results indicated that the silk I structure remains stable only when the Y residue is positioned near the chain terminus; otherwise, a silk I --> silk II conformational transition occurs. The peptides AGVGAGYGAGVGAGYGAGVGAGYG(AG)3 and (AG)3YG(AG)2VGYG(AG)3YG(AG)3 treated with LiBr revealed a prevalent silk II conformation; moreover, the former contained a higher amount of random coil than the latter. This result was explained in relation to the different degrees of interruption of the (AG)n sequence. The Raman analysis of the AGSGAG-containing samples confirmed that the AGSGAG hexapeptide is a good model for the silk II crystalline domain. As the number of AGSGAG repeating units decreased, the random coil content increased. The study of the Y domain (I850/I830 intensity ratio) allowed us to hypothesize that in the packing characteristic of Silk I and Silk II conformations the Y residues experience different environments and hydrogen-bonding arrangements; the packing typical of silk I structure traps the tyrosyl side chains in environments more unfavorable to phenoxyl hydrogen-bonding interactions.

Animals↗