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M Yvon

Publications and source records attributed to M Yvon.

27 records · Page 2Linked to original sources
PubMed1990

Identification of the binding sites of benzyl penicilloyl, the allergenic metabolite of penicillin, on the serum albumin molecule.

Tryptic digests of fragment A299-585 of penicilloylated serum albumin obtained from two penicillin-treated patients or prepared by in vitro conjugation, were analyzed by a tandem immunoaffinity reversed-phase HLPC. Determinations of benzyl penicilloyl groups (BPO) were performed on the different fractions. Three BPO containing peptides were identified by their amino acid sequence and the bound BPO were located on lysines 432, 541 and 545. Six major BPO binding sites were thus identified on the whole albumin molecule. All of them are lysine residues and correspond to a limited number of definite structures in which lysine and serine residues appear to be closely associated.

Amino Acid Sequence↗
PubMed1989

Binding of benzyl penicilloyl to human serum albumin. Evidence for a highly reactive region at the junction of domains 1 and 2 of the albumin molecule.

Tryptic digests of fragment C124-298 of penicilloylated serum albumin, obtained from a penicillin-treated patient or prepared by in vitro conjugation, were analyzed by HPLC. Determinations of benzyl penicilloyl groups (BPO) were performed on the different fractions. Three BPO-containing peptides were identified by their amino acid sequence and the bound BPO was located on lysines 190, 195 and 199 and serine 193. These four main BPO-binding sites are all located on a very short region (10 amino acid residues) of the albumin molecule at the junction of domains 1 and 2.

Amino Acid Sequence↗
PubMed1989

Solubility of peptides in trichloroacetic acid (TCA) solutions. Hypothesis on the precipitation mechanism.

The assessment of proteolysis levels is often achieved by global quantification of the peptides soluble at different TCA concentrations, but little information is available on the features of this precipitation mechanism. Peptic, tryptic and chymotryptic digests of alpha s1, beta, and kappa caseins have been prepared and fractionated by RP-HPLC and each isolated peptide was identified. Each digest was precipitated by adding TCA to different final concentrations (2, 4, 8, and 12%). The soluble fraction was analysed by RP-HPLC. Relationships have been searched between the properties of 75 peptides obtained in this way, and their solubilities in TCA. The best correlation was found with the peptide retention time in RP-HPLC, which can be regarded as the experimental measure of peptide hydrophobicity. We concluded that TCA, by interacting with peptides, induces an increase of the hydrophobicity of peptides which can lead to aggregation through hydrophobic interactions.

Amino Acid Sequence↗
PubMed1986

[Digestion of milk proteins in the abomasum of the preruminant calf].

Gastric digestion of milk proteins has been studied in the preruminant calf by analysing gastric effluents in the duodenum after the ingestion of 5 different diets: whole milk, skim milk, casein solution in water, casein solution with minerals, whey. The amino acid composition of the gastric effluents and HPLC analysis of the latter show that the major part of the whey proteins were evacuated rapidly without any proteolysis and after milk ingestion. On the contrary, all the caseins were largely proteolysed and arrived slowly in the gut. The major part of the peptides obtained came from alpha s1 casein. Only a few peptides, principally CMP, were quickly emptied from the stomach.

Abomasum↗
PubMed1985

In vivo milk digestion in the calf abomasum. III. Amino acid compositions of the digesta leaving the abomasum.

Calves were fed five different test meals: whole milk, skim milk, 3% whole casein solution, 3% whole casein in simulated milk ultrafiltrate, and whey. The digesta leaving the abomasum before feeding and during the first 7 postprandial hours were collected by fractions. After precipitation with 12% TCA, the amino acid compositions of the sediments and the supernatants were determined and compared by multivariate analysis. The composition of prefeeding digesta was similar to that of gastric juice. When the calves were fed the two casein diets, the amino acid composition of the sediments changed little with time. In contrast, the changes observed in the composition of the supernatants suggested rapid abomasal emptying of caseino-macro peptide. With the whey diet, it was not possible to evidence more rapid hydrolysis or abomasal emptying of any particular whey protein. During the first 10 min following the ingestion of whole or skim milk, the amino acid composition of the sediment was close to that of milk protein. Immediately afterwards, the composition of the sediment was similar to that of whey protein. Thereafter, the composition of the sediment became more like that of casein and almost reached that of casein during the 7th hour. The amino acid composition of the supernatant was similar to that obtained with the casein diets; this fact suggests that the small peptides produced by proteolysis in the abomasum originated more from casein than from whey proteins.

Abomasum↗
PubMed1984

In vivo milk digestion in the calf abomasum. I. Whole-casein digestion.

Peptide products insoluble in 12% TCA and obtained in the proximal duodenum of calves at different times after ingestion of casein solutions were characterized by polyacrylamide gel electrophoresis, electrofocusing and SDS pore gradient gel electrophoresis. With a 3% whole-casein solution in water the disappearance of electrophoretic bands corresponding to alpha s1 and beta caseins was observed after about 1 h 30. After 3 h and up to 7 h very acidic peptides appeared. With a 3% whole-casein solution in simulated milk ultrafiltrate, comparable patterns were obtained. Nevertheless, the acidic peptides appeared sooner, i.e. they were already detected in the first sample collected after meal ingestion. With the 2 diets, the importance of gastric proteolysis was demonstrated by the appearance of a great number of peptides of various sizes, charges and pHi. On the other hand, an effect of salts on casein proteolysis was detected.

Abomasum↗