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C Roustan

Publications and source records attributed to C Roustan.

At least 73 records · Page 4Linked to original sources
PubMed1983

Induction by chemically modified actin derivatives of antibody specificity. A relation between modified sites and antibody interactions with monomeric and filamentous actins.

A comparison of specific antibodies induced by unfolded actins modified either by oxidation or by arylation of lysine residues was reported. We have focused our work on binding properties with filamentous actin and located its preferential antigenic sites for the anti-arylated-actin antibodies in the C-part of the molecule. An interference of anti-oxidized actin antibodies upon actin polymerisation has also been reported.

Actins↗
PubMed1982

Interaction of yeast 3-phosphoglycerate kinase with negatively charged carriers.

The aim of this study was to investigate the possibility of an interaction of yeast 3-phosphoglycerate kinase with negatively charged carriers such as polyanionic agents or a polarized electrode. Various polyanions were found to promote enzyme aggregation as judged by ultracentrifugation measurements and chemical modification. The data obtained suggest that these interactions are mediated through the N-terminal domain of the protein. However, the most striking property of 3-phosphoglycerate kinase described here is concerned with its significant dipolar moment as evidenced by electrocapillary measurements, which allows an orientation of the macromolecule in an electric field. Further, the enzyme could be absorbed by a negatively charged surface, first by hydrophobic links and then oriented perpendicularly to the surface. Therefore, the intrinsic properties of yeast 3-phosphoglycerate kinase agree with the formation of an enzyme-membrane complex and afford the ability for a specific orientation of the molecule at the lipid bilayer surface or in the cytoplasm.

Chondroitin Sulfates↗
PubMed1982

Isolation and structural properties of a high-molecular-weight actin-binding protein (filamin-like protein) in hog thyroid gland.

A high-molecular-weight protein has been isolated from hog thyroid gland. This protein, with a molecular weight of 475,000 determined by ultracentrifugation and gel filtration, is a complex of two polypeptides with apparent molecular weights of 250,000 and 240,000. It may be related to filamin-like proteins by its physicochemical properties and its immunogenic cross-reactivity towards gizzard filamin antibodies. Furthermore it interacts with F-actin in a stoichiometry of 1 mol of high-molecular-weight protein/approximately 12-14 mol actin monomer allowing microfilament association, as shown by electron microscopy.

Animals↗
PubMed1981

Structural studies on yeast 3-phosphoglycerate kinase. Linear arrangement of the CNBr fragments, partial amino acid sequence of the inner part of the polypeptide chain, and analyses of the N-terminal domain of the protein.

The purpose of this work was to contribute to the study of the covalent structure of yeast 3-phosphoglycerate kinase. First, we undertook the complete alignment of the four fragments produced by cyanogen-bromide cleavage and which constitute the intact protein; we then established the total amino acid sequence of a 30-residue peptide and the N-terminal sequence of a 65-residue peptide. Second, we analyzed the acetylated state of the protein. The analyses of the acid fraction "P" obtained after digestion of 3-phosphoglycerate kinase by pronase enabled us to determine the N-terminal sequence of this enzyme as N-acetylserylglycine. Third, we isolated, purified and analyzed seven tryptic peptides from a fragment containing 102 amino acids coming from the N-terminal end of the protein. The peptides occupying the N- and C-terminal ends of this fragment were also identified.

Amino Acid Sequence↗
PubMed1980

Yeast 3-phosphoglycerate kinase: sulfate and substrate binding, their effect on the conformational state of the enzyme.

Anions and particularly sulfate are known to interact with 3-phosphoglycerate kinase and to induce an increase of its catalytic efficiency. The present work affords information on the location of the anionic site and on the conformational change produced by the sulfate binding. We have established that sulfate is able, first, to modify the environment of some critical amino acids (cysteine and arginines) located in the N-terminal half of the protein, second, to induce perturbation of aromatic residues as judged by spectrophotometry, and, third, to slightly decrease the magnitude of the Cotton effect at 233 nm. All these modifications are produced by sulfate concentrations required for the activation of the enzyme. The most striking result consists in a large change in the hydrodynamic properties of the protein upon sulfate interaction as determined by analytical ultracentrifugation studies. Thus, sulfate modifies the shape of the molecular, causing it to become more compact. Furthermore, a study of the binary and ternary complexes between yeast 3-phosphoglycerate kinase and its substrates suggests that such a change of the shape of the molecular only occurs in sulfate-enzyme with or without substrates and in ATP (with or without Mg2+)-3-phosphoglycerate-enzyme complexes.

Binding Sites↗
PubMed1980

Structural studies on yeast 3-phosphoglycerate kinase. Identification by immuno-affinity chromatography of one glutamyl residue essential for yeast 3-phosphoglycerate kinase activity. Its location in the primary structure.

3-Phosphoglycerate kinase is inactivated by 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate and nitrotyrosine ethyl ester. The coupling of 1 mol nitrotyrosine/mol enzyme is sufficient to inactivate the protein completely. A weak protection against inactivation is observed with each substrate added separately. In contrast, the complex ATP--3-phosphoglycerate--enzyme or ATP--Mg--3-phosphoglycerate--enzyme affords a considerable protection. The critical residue is identified as a glutamyl residue after isolation by immuno-affinity chromatography of nitrotyrosyl peptide resulting from exhaustive proteolytic digestion of the modified protein. In addition, the determination of the primary sequence of the C-terminal part of the protein leads to the location of the glutamyl residue at position eight from the C-terminus. We conclude that this glutamyl residue is situated in the domain which does not bind the nucleotide substrates [Bryant, T.N., Watson, H.C. and Wendell, P.L. (1974) Nature (Lond.) 247, 14--17]. Its role in the catalysis process is discussed.

Amino Acid Sequence↗
PubMed1979

Spatial proximity of a tyrosyl and a lysyl residue in the active site region of yeast 3-phosphoglycerate kinase.

The effect of 7-chloro-4-nitrobenzofurazan on yeast 3-phosphoglycerate kinase causes a modification of one tyrosyl residue concomitantly with a total loss of activity of the enzyme. The modification is not accompanied by any significant conformational change. A total protection against inactivation is observed with the substrates : furthermore, AMP, tripolyphosphate and pyrophosphate afford an effective protection. At pH 9, a shift in the absorbance spectrum of the tyrosine O-nitrobenzofurazan derivative of 3-phosphoglycerate kinase is observed. It can be related to the transfer of the reagent from tyrosine to lysine. The N-nitrobenzofurazan derivative is also completely inactive. It is concluded that a lysine residue is located close to the essential tyrosyl residue.

4-Chloro-7-nitrobenzofurazan↗
PubMed1978

Yeast 3-phosphoglycerate kinase. Essential arginyl residues at the 3-phosphoglycerate binding site.

Yeast 3-phosphoglycerate kinase (ATP:3-phospho-D-glycerate 1-phospho-transferase, EC 2.7.2.3) is inactivated by phenylglyoxal. Loss of activity correlates with the modification of two arginyl residues, both of which are protected by all of the substrates. The modification is not accompanied by any significant conformational change as determined by optical rotatory dispersion. Ultraviolet difference spectrophotometry indicates that the inactivated enzyme retains its capacity for binding the nucleotide substrates whereas the spectral perturbation characteristic of 3-phosphoglycerate binding is abolished in the modified enzyme. The data suggest that at least one of the two essential arginyl residues is located at or near the 3-phosphoglycerate binding site. A likely role of this residue could be its interaction with the negatively charged phosphate or carboxylate groups of 3-phosphoglycerate.

Arginine↗
PubMed1978

Structural studies on yeast 3-phosphoglycerate kinase. Isolation by affinity chromatography and characterization of the peptides produced by cyanogen bromide cleavage. Location of the single cysteinyl residue in the primary structure.

Cyanogen bromide cleavage of yeast 3-phosphoglycerate kinase yielded four fragments which account for the amino acid composition of the entire molecule. These results are consistent with a single polypeptide chain of molecular weight 42 000. Affinity chromatography on Sepharose-mercurial followed by gel filtration on Sephadex was used with success for separation of peptides. The carboxyl and N-terminal fragments were characterized. The N-terminal fragment contained the single cysteinyl residue of the protein. After cyanylation and subsequent cleavage, this cysteinyl residue was located near position 100.

Amino Acid Sequence↗
PubMed1977

Evidence for an essential glutamyl residue in yeast hexokinase.

Yeast hexokinase is rapidly inactivated by 1-cyclohexyl-3-(2-morpholinoethyl)carbodiimide metho-p-toluenesulfonate and nitrotyrosyl ethyl ester. Sugar substrates afford a partial protection, which is increased by the addition of ADP. Inactivation of the enzyme takes place concomitantly with the incorporation of 1 mol of nitrotyrosine per mol of 50 000-dalton subunit. Exhaustive proteolytic digestion of the modified protein and isolation of the nitrotyrosyl peptide by affinity chromatography, followed by electrophoresis, lead to the identification of the modified residue as a glutamyl residue. This modification of hexokinase occurs without gross conformational changes. The enzyme still binds its substrates, though binding of the nucleotides is perturbed. While the substrates afford a partial protection, they increase the incorporation of nitrotyrosine ethyl ester into the enzyme. This may be attributed to local conformational changes which their binding induces. It is concluded that a glutamyl residue is essential for yeast hexokinase activity and its catalytic function is discussed.

Binding Sites↗
PubMed1977

[Identification of an essential glutamate residue in the 3-phosphoglycerate kinase of yeast].

The incorporation of nitrotyrosine into 3-phosphoglycerate kinase activated by carbodiimide results in the chemical modification of a single essential residue. After total proteolytic digestion, isolation of the dipeptide gamma Glu-NO2 Tyr by immuno-affinity chromatography indicates the implication of a glutamyl residue. It is interesting to point out the applicability of the method described for the purification of peptides containing carboxyl residues.

Binding Sites↗
PubMed1976

Physicochemical and kinetic properties of iodinated yeast 3-phosphoglycerate kinase.

The present studies have established that there is a critical tyrosyl residue in yeast 3-phosphoglycerate kinase. The iodination of this enzyme results in an inactivation following first-order kinetics. The extent of the modification is limited to only one tyrosyl residue. The monoiodotyrosine formation which leads to inactivation of the enzyme does not induce any significant conformational change as evidenced by hydrogen exchange and optical rotatory dispersion. The role of this tyrosine in the action of the yeast 3-phosphoglycerate kinase is studied. An effective protection against inactivation is observed with 3-phosphoglycerate, and the characteristic spectral effect of 3-phosphoglycerate binding cannot be detected in the modified enzyme. It is concluded that the essential tyrosyl residue may play a role in substrate binding.

Amino Acids↗
PubMed1975

Muscle pyruvate kinase: interaction with substrates and analogues studied by difference spectroscopy. Comparative studies of the substrate-binding sites of various ATP phosphotransferases.

The substrate binding sites of pyruvate kinase have been studied by means of spectrophotometric investigations. Two binding sites, one for the nucleotide substrate and one for the acceptor, have been characterized. The interaction of nucleotide substrates with the enzyme, which is metal-dependent, results in a perturbation of the spectrum of the nucleotide chromophore characterized by hypochromic and red shift effects; the hydrophobicity of the nucleotide site was estimated by using a reporter group reagent, 2-(dansylamino)ethyl monophosphate. The comparison between the binding sites of several ATP phosphotransferases is discussed and some common features are reported.

Adenosine Diphosphate↗