title: Interindividual variability of enkephalin-degrading enzymes in human plasma.
abstract: The interindividual variability of the hydrolysis of leucine enkephalin, and of the formation of its hydrolysis by-products has been studied in human plasma. In agreement with known data, the data obtained indicate that Leu-enkephalin is degraded by several enzymes, belonging to three classes: aminopeptidases, dipeptidylaminopeptidases, and dipeptidylcarboxypeptidases. The relative ratio of the substrate degraded by each enzyme class-as well as the expression of the single enzyme species within each class-appears to be individually determined. Interindividual variability observed seems controlled by two main factors: the pattern of enkephalin-degrading enzymes and, more notably, the low molecular weight plasma inhibitors. Both these factors appear to be partially specific of each donor. Possibly because of the composition of these factors, the hydrolysis pattern of the substrate is characteristic of each donor, and constant in blood obtained from successive drawings, at least within a relatively short period of time.
authors.affiliation: Dipartimento di Medicina Sperimentale, Universitá degli Studi di Roma Tor Vergata, Italy.
authors.forename: M
authors.initials: M
authors.lastname: Marini
authors.forename: A
authors.initials: A
authors.lastname: Urbani
authors.forename: E
authors.initials: E
authors.lastname: Trani
authors.forename: L
authors.initials: L
authors.lastname: Bongiorno
authors.forename: L G
authors.initials: LG
authors.lastname: Roda
mesh_terms: D000328:Adult; D000626:Aminopeptidases / Q000097:blood; D005591:Chemical Fractionation; D003627:Data Interpretation, Statistical; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases / Q000097:blood; D010450:Endopeptidases / Q000097:blood; D004745:Enkephalins / Q000097:blood*; D005260:Female; D006801:Humans; D006868:Hydrolysis; D016014:Linear Models; D008297:Male; D008875:Middle Aged; D008970:Molecular Weight; D010949:Plasma / Q000201:enzymology*; D011480:Protease Inhibitors / Q000097:blood / Q000302:isolation & purification; D015203:Reproducibility of Results; D013379:Substrate Specificity
chemical_list: D004745:Enkephalins; D011480:Protease Inhibitors; D010450:Endopeptidases; D000626:Aminopeptidases; D004152:Dipeptidyl-Peptidases and Tripeptidyl-Peptidases; C020071:dipeptidyl carboxypeptidase