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Biomedical subjects

J P Perraudin

Publications and source records attributed to J P Perraudin.

At least 19 recordsLinked to original sources
PubMed1990

Anomerization and hydrolysis of lactose by beta-galactosidase from Saccharomyces lactis.

Beta-Galactosidase from Saccharomyces lactis was found to be able to catalyze both the anomerization of alpha-lactose and the hydrolysis of beta-lactose; the rate of hydrolysis appeared to be four times higher with a 1:1 mixture of alpha and beta lactose than with a freshly prepared solution of alpha-lactose. The enzyme was also found to be unable to hydrolyze alpha-lactose. Thus, it appears that beta-galactosidase from S. lactis has its hydrolytic activity on lactose adapted only to the naturally more abundant beta-lactose.

Galactosidases↗
PubMed1990

Treatment of induced enterotoxigenic colibacillosis (scours) in calves by the lactoperoxidase system and lactoferrin.

The clinical efficacy of a preparation based on the lactoperoxidase system (LP-s) and lactoferrin (LF) was tested in calves experimentally infected with E coli K99+, Ent+. Mortality, occurrence and duration of diarrhoea were significantly lower (P less than 0.05) and general clinical status significantly better (P less than 0.05) in infected calves treated with LP-s and LF preparation than in infected but non-treated calves. Results suggest that LP-s and lactoferrin are effective in the treatment of enteric colibacillosis in calves.

Animals↗
PubMed1983

Multiple parameter kinetic studies of the oxidative folding of reduced lysozyme.

We have compared the oxidative renaturation of reduced hen egg white lysozyme promoted by Cu(II) + O2 with that promoted by a glutathione redox buffer. The progress curves for protein fluorescence, circular dicroism, thiol oxidation, hydrodynamic volume, and enzymic activity were determined for both regeneration systems. All of these processes were more rapid in the glutathione regeneration than in the copper-catalyzed. Comparison of the two systems was carried out by normalizing the progress curves with a coordinate system where "time" is replaced by "extent of protein thiol oxidation." While similar progress curves were obtained for circular dichroism, the two systems produced distinctly different progress curves for enzymic activity, fluorescence, and gel permeation chromatographic reflection of protein hydrodynamic volume. We infer that all these differences result from differences in relative amounts and/or kind of reaction intermediates. Thus, there are substantial differences between the renaturation mechanisms of the glutathione- and the copper-promoted systems.

Animals↗
PubMed1983

Disulfide content of reduced hen egg white and human milk lysozymes during the folding process.

In order to obtain a better understanding of the possible influence of the primary sequence of a protein on its folding pathway, renaturation of reduced human milk lysozyme was compared to that of reduced hen egg white lysozyme. Following disulfide bond formation, under identical conditions, similar products were found during the folding of both lysozymes, but the kinetics of appearance and disappearance of these intermediates as well as the appearance of the native conformation were different.

Amino Acid Sequence↗
PubMed1983

Enzymic properties of an N-acetylglucosaminide 3-alpha-L-fucosyltransferase of a wheat-germ agglutinin-resistant melanoma clone.

A fucosyltransferase was solubilized by extraction with Triton CF-54 from a wheat-germ agglutinin-resistant variant of mouse B16 melanoma. Through affinity chromatography on GDP hexanolamine--Sepharose a 44-fold enrichment of its specific activity was obtained. Analysis of its specificity indicated that the enzyme is an N-acetylglucosaminide 3-alpha-L-fucosyltransferase, which is able to transfer fucose to oligosaccharides containing Gal(beta 1-4)GlcNAc and Gal(beta 1-4)Glc structures. The enzyme is activated by divalent cations and has a maximum of activity at pH 5. It is unable to transfer fucose to sialylated glycoproteins, 6-alpha-sialyllactose or 3-alpha-sialyllactose. As suggested by its precipitation in the presence of antibodies raised in rabbit against a soluble human milk N-acetylglucosaminide 3-alpha-L-fucosyltransferase, these two enzymes seem to be structurally related.

Agglutination Tests↗
PubMed1982

Comparison between the folding of reduced hen egg white lysozyme and that of reduced human milk lysozyme.

In vitro, renaturation of reduced and unfolded lysozyme is catalyzed by a mixture of reduced and oxidized glutathione. After initiation of disulfide bond formation associated with the folding process of reduced human lysozyme, molecules have been trapped in a stable form with iodoacetic acid (preserving disulfide bonds) at various times of reoxidation. Each population of molecules trapped in this way was then analyzed by acrylamide gel electrophoresis which separates intermediates on the basis of the number of disulfide bonds they contain and the mean volume of the polypeptide chain. Moreover, the rate of reoxidation of the regeneration mixture was monitored by changes in enzymatic activity, fluorescence quantum yield, and global sulfhydryl group titer. Enzymatic activity was observed to appear after an induction period, and no intermediate, except the fully regenerated species, is active. The first two disulfide bonds reoxidize rapidly, and very few intermediates containing one or two disulfide bonds could be trapped. On the other hand, the intermediates containing three and four disulfide bonds are more predominant, and their formation proceeds more slowly. A folding pathway is suggested, based on the kinetic studies of appearance and disappearance of the various observed intermediates. When these results are compared with those obtained for hen egg white lysozyme and with those found in literature, it can be concluded that the reduced human protein recovers its native conformation more progressively and with more difficulty than the hen egg white protein. This difference might be explained by a greater organization and a greater hydrophobicity in the human molecule.

Animals↗
PubMed1982

Lactoferrin binding to lysozyme-treated Micrococcus luteus.

When the cell lysis of Micrococcus luteus by hen egg white or human lysozyme is performed in the presence of bovine or human lactoferrin, a temporary increase of the turbidity of the solution as followed at 450 nm is observed. Examination of the suspension under light microscopy has proven that the protoplasts produced upon lysozyme action are agglutinated by lactoferrin. The rate of agglutination depends on pH, lactoferrin, lysozyme and cells concentrations. Agglutination is maximal at pH 5.5. Around 1.4 X 10(6) binding sites for lactoferrin per cell have been determined through a Scatchard plot analysis. The binding to the cells is not mediated by the glycosidic moiety of lactoferrin but rather by a charge-to charge interaction as succinylation of about four out of the 39 lysines of lactoferrin completely abolishes its ability to agglutinate the cells. Binding does not depend on ionic iron nor on the iron content of lactoferrin itself.

Animals↗
PubMed1978

Reoxidation of reduced hen egg white lysozyme fragment 1-123.

The reactivation of reduced lysozyme, whose 6 COOH-terminal amino acid including cysteine 127 were cut off, was studied. The results show that the disulfide bridge I-VIII as well as the COOH-terminal hexapeptide do not play a decisive role in the acquisition of the native 3-dimensional structure of the enzyme.

Animals↗