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Biomedical subjects

Y Robin

Publications and source records attributed to Y Robin.

At least 37 records · Page 2Linked to original sources
PubMed1977

[Antigenic activity of lobster (Homarus vulgaris) arginine kinase and its cyanogen bromide fragments].

The antigenic saturation of lobster arginine kinase (38 000 daltons) by its specific antibodies has been studied. It was found that seven antigenic binding sites are simultaneously reactive on the surface of the enzyme in the presence of a large excess of antibodies or of their Fab fragments. After cyanogen bromide cleavage, the antigenic reactivity is distributed on several fragments of various sizes.

Animals↗
PubMed1977

[Effect of guanidine dderivatives on choline acetylase and acetylcholinesterase of the rabbit brain].

The effects of 14 guanidino compounds on the activity of rabbit brain choline acetyltransferase (CAT) and acetylcholine esterase (ACE) have been studied, comparatively with that of pentylentetrazol. No guanidino compound examined nor pentylentetrazol had an effect on CAT activity. 4 of them showed a moderate inhibitory effect on ACE, of the same order of magnitude as that of pentylentetrazol, but significantly lower than that of the specific inhibitors eserine and mytelase.

Acetylcholinesterase↗
PubMed1976

An approach to the antigenic structure of arginine kinase and creatine kinase. Physical, chemical and immunological study of some modified derivatives.

The antigenic structure of arginine kinase and creatine kinase has been approached using chemical modifications and enzymatic cleavage. Mild performic oxidation that, with a restricted number of oxidized amino acid residues, results for both enzymes in a severe decrease of the helical structure and in a large increase of the protein-solvent interactions, affects differently their antigenic reactivity: when compared with antisera to the homologous native enzymes, arginine kinase and its oxidized derivative cross-react fully, while creatine kinase and its oxidized derivative cross-react only about 30%. The persistence of the antigenic reactivity of arginine kinase through drastic structural alterations is confirmed by the high inhibitory capacity (about 80%) of crude tryptic hydrolyzates towards the combination of argining kinase with its specific antibodies. Tryptic peptides of creatine kinase, obtained in the same conditions, inhibit weakly (about 12%) the homologous antigen-antibody interaction. The participation of the lysines in the antigenicity of arginine kinase and creatine kinase is suggested by the enhanced inhibitory capacity of the tryptic hydrolyzates when the cleavage is restricted to the arginyl peptide bounds, and was verified for arginine kinase through assays with lysine-modified derivatives.

Amino Acids↗
PubMed1976

[Transovarian transmission of a Flavivirus, the Koutango virus, in Aedes aegypti L].

The Koutango virus Dak An D 5443 isolated from rodents of the genus Tatera belongs to the genus Flavivirus of the faily Togaviridae. This virus is very similar to the yellowfever, virus. It is experimentally transmitted from young Mouse to young Mouse by Aedes aegypti. The following observations show on one hand that this virus is found in the eggs of infected A. aegypti and on the other that the females from these eggs transmit the virus to the young Mouse by biting them.

Aedes↗
PubMed1976

Inhibition of lobster-muscle arginine kinase by homologous antibodies and study of an antibody population directed against a tyrosine-containing antigenic structure.

The effect of highly inhibitory rabbit antibodies on the enzymic activity of lobster-muscle arginine kinase has been studied. 100% inhibition was obtained at a 30-fold molar excess of antibody. The guanidine substrate L-arginine did not protect the enzyme from subsequent inhibition by its antibodies. On the other hand, the metal-nucleotide substrate Mg-ATP, or the substrate analog Mg-AMP, protected about 50% the enzyme activity, the extent of hte protection being irrespective of hte presence or of the absence of L-arginine and of the value of the molar ration Ab/Ag/ An antibody population directed against the antigenic determinant containing the essential tyrosine residue of the enzyme has been isolated by the affinity chromatography. No inhibitory acitivity was found in that fraction. Most of the inhibitory activity was found in the remaining antibody populations...

Animals↗
PubMed1976

[Effect of phascoline and phascolosomine, new natural guanide derivatives, on cultured rat cardiac cells].

Two new biological guanido compounds from sipunculid worms, phascocoline [N-(3-guanidinopropionyl)-2-hydroxy-n-heptylamine] and phascolosomine [N-(3-guanidinoisobutyryl)-2-methoxy-n-heptylamine], have been tested for their effect on cultured rat heart cells. Both compounds were found to stop the beating of the cells at concentrations greater than or equal 10(-3) M, the effect being observed after 30 minutes for phascolosomine and after 24 hours for phascoline. At 10(-4) M concentration, the same compounds did not stop the beats but slowed the rhythm after 24 hours of contact. Assays performed with the hydrolysis products of phascoline and phascolosomine, beta-guanidinopropionic acid and 2-hydroxyheptylamine for the former, and beta-guanidinoisobutyric acid and 2-methoxy-n-heptylamine for the latter, have shown that the biological activity is located in the aminoalcool or aminoether moiety of the molelcule. It has been found that the effect on cultured rat heart cells was reversible at concentrations less than or equal 10(-3) M.

Animals↗
PubMed1975

[A strain of amaril virus isolated from Aedes africanus in the Ivory Coast].

The yellow fever virus has been isolated from a pool of Aedes africanus caught on men in a region situated between forest and savannah near Touba, in the Ivory Coast. This isolation, occurring at an interepidemic period, proves for the first time in West Africa, the part played by this mosquito in the transmission of the yellow fever virus.

Aedes↗
PubMed1975

Unspecific arginine kinase of molecular weight 150 000. Amino acid composition, subunit structure and number of substrate binding sites.

The amino acid composition of unspecific arginine kinase of molecular weight 150 000 of Sabella pavonina muscle has been determined. If was found to be very similar to that of the phosphagen kinases previously studied. The subunit structure of the enzyme has been investigated by physical and chemical means. The data obtained from ultracentrifugation studies in 6 M guanidine hydrochloride and from molecular sieving and disc electrophoresis in 8 M urea, as well as the tryptic peptide mapping, suggest that Sabella muscle kinase is composed of four non-covalently linked polypeptide chains, with similar molecular weights. The number of binding sites for the nucleotide substrate ADP-Mg2+ has been estimated, using differential spectrophotometry and gel filtration on Sephadex columns. By both methods it was demonstrated that the enzyme contains two catalytic sites per protein molecule of molecular weight 150 000. Thus, arginine kinase from Sabella muscle, of molecular weight 150 000, consists of four similar polypeptide chains, but possesses only two substrate binding sites per tetrameric molecule.

Adenosine Diphosphate↗
PubMed1975

Effect of substrate - binding on the immunologic reactivity of lobster - muscle arginine kinase : a comparison with rabbit - muscle creatine kinase.

The effects of substrate-binding upon the immunologic reactivity of rabbit creatine kinase and lobster arginine kinase have been investigated. The separate binding of the guanidine or the nucleotide substrate to creatine kinase yields no alteration of antigenicity and a substantial effect is only observed when all the loci at the active center of the enzyme, including that for the transferable phosphoryl group, are occupied. In contrast, the antigenic reactivity of arginine kinase is affected by the separate binding of either the guanidine or the nucleotide substrate, and the simultaneous binding of the two substrates results in a cumulative effect, which is irrespective of the phosphorylated or non-phosphorylated form of the complex. These results support the existence of substrate-induced conformational changes demonstrated by other methods, and they reveal appreciable differences in their effect on the antigenic reactivity of the two enzymes.

Animals↗