Biomedical subjects

R Possenti

Publications and source records attributed to R Possenti.

24 records · Page 2Linked to original sources

PubMed1985

Peripheral enkephalin hydrolysis in different animal species: a comparative study.

Using column and thin layer chromatography, plasma hydrolysis of leu-enkephalin has been studied in man and several laboratory animals. The hydrolysis kinetics determined in the various species examined are considerably different. In addition, also the enzyme forms evidentiated, their molecular weight distribution and relative ratios have been found to vary greatly in the animals under test. Our data suggest that the widely different hydrolysis kinetics reported by various authors are attributable to the differences between species, rather than to differences in the analytical techniques employed.

Aminopeptidases↗

PubMed1985

Enkephalin binding systems in human plasma. II: Leu-enkephalin serum albumin interaction.

Enkephalins are released into the bloodstream of mammals by the adrenal medulla. Once they are in the blood, these peptides undergo a fairly rapid hydrolysis by several plasma-contained enzymes. However, a fraction of the enkephalins present in the plasma are bound to the serum albumin, and the bound peptides are almost completely intact even after a long incubation in the presence of serum enzymes. Therefore, it seems possible that the interaction with serum albumin can maintain the functional integrity of the circulating enkephalins. Moreover, serum albumins are extremely well characterized proteins and, therefore, a suitable model for the study of protein-enkephalin interaction in general. The present work is a first step in the study of the mechanism of serum albumin-enkephalin interaction. Apparently, ionic parameters are important in the binding phenomenon. Furthermore, the serum albumin conformational status seems to be relevant in the binding. Finally, the binding is followed by a limited rearrangement of the protein molecule.

Acylation↗

PubMed1985

Mechanisms of leu-enkephalin hydrolysis in human plasma.

The present work describes the kinetics of enkephalin hydrolysis by plasma enzymes and the fragmentation pattern of both the parent peptide and of the first hydrolysis by-products. The degradation kinetics were followed by positive identification of the hydrolysis fragments by chromatographic methods, by amino acid analysis and by scintillation counting of tritium-labeled enkephalin. In addition, the results presented confirm the role of the low molecular weight plasma components in the control of the hydrolysis of the peripherally-released enkephalins.

Amino Acids↗

PubMed1984

A cell division-active protein from E. coli.

A purification procedure for a protein obtained from an pathogenic strain of E. coli is described. The protein-called CNF-is active in inhibiting the duplication of cultured mammalian cells. Since nuclei division is apparently normal, treatment of cultured cells with CNF leads to the formation of gigantic, polynucleated cells. The purified protein is chromatographically and electrophoretically homogeneous. A partial characterization of CNF protein is also given.

Amino Acids↗

PubMed1984

In vitro interaction of opioid peptides with phospholipids. Formation and characterization of complexes.

Interaction of Leu- and Met-enkephalin with phosphatidylserine has been studied by chromatographic and spectrophotometric techniques. The main results of our investigation may be summarized as follows: i) Both enkephalins bind to phosphatidylserine; ii) no difference between the two enkephalins is noticeable; and iii) with both peptides the binding phenomenon leads to the formation of two complexes with a definite stoichiometry which are sterically much smaller than the original vesicles. On the basis of the submitted data, a tentative model of the newly formed complexes is provided.

Acylation↗

PubMed1983

Enkephalin-binding systems in human plasma.

Three amino acid-containing fractions present in human plasma are shown to bind both leu and met-enkephalin: serum albumin and two species of a much lower molecular weight, in all likelihood polypeptides. The amount of enkephalin associated with serum albumin seems comparatively smaller than that associated with the two low molecular weight systems. These systems jointly are apparently capable of binding a significant part of the circulating enkephalins. The possibility is suggested that the interactions described may play a role in maintaining the integrity of circulating enkephalins.

Amino Acids↗