title: [Leu-enkephalin homogeneously labeled with tritium in studying the Selank inhibiting effect on the enkephalin-degrading enzymes of human plasma].
abstract: A method of analysis of enkephalinase activity in blood plasma based on the application of Leu-enkephalin generally labeled with tritium at all its amino acid residues was developed. The method allows the simultaneous estimation of activity of several peptidases in microquantities of tissues. [G-3H]Leu-enkephalin was prepared by the method of solid phase catalytic isotope exchange (120 Ci/mmol) and subjected to proteolysis by the treatment with blood plasma. The resulting radioactive metabolites were separated by HPLC in the presence of the mixture of unlabeled fragments of Leu-enkephalin as internal standards. It was shown that aminopeptidases, dipeptidylaminopeptidases, and dipeptidylcarboxypeptidases respond for approximately 80%, 2%, and 10% of the total enzymatic activity, respectively. The new pathway of degradation of Leu-enkephalin by carboxypeptidase that provides for approximately 6% of the total enkephalin-degrading activity was discovered. Bestatin was shown to predominantly inhibit aminopeptidases and carboxypeptidases, whereas Selank is more specific for carboxypeptidases and dicarboxypeptidases. The English version of the paper: Russian Journal of Bioorganic Chemistry, 2004, vol. 30, no. 3; see also http://www.maik.ru.
authors.forename: Iu A
authors.initials: IuA
authors.lastname: Zolotarev
authors.forename: O Iu
authors.initials: OIu
authors.lastname: Sokolov
authors.forename: N V
authors.initials: NV
authors.lastname: Kost
authors.forename: B V
authors.initials: BV
authors.lastname: Vas'kovskiĭ
authors.forename: N F
authors.initials: NF
authors.lastname: Miasoedov
authors.forename: A A
authors.initials: AA
authors.lastname: Zozulia
mesh_terms: D000626:Aminopeptidases / Q000037:antagonists & inhibitors; D004743:Enkephalin, Leucine / Q000737:chemistry / Q000378:metabolism*; D020689:Exopeptidases / Q000097:blood* / Q000187:drug effects* / Q000378:metabolism; D006801:Humans; D007930:Leucine / Q000031:analogs & derivatives* / Q000494:pharmacology; D009842:Oligopeptides / Q000494:pharmacology*; D011480:Protease Inhibitors / Q000494:pharmacology*; D014316:Tritium
chemical_list: D009842:Oligopeptides; D011480:Protease Inhibitors; D014316:Tritium; D004743:Enkephalin, Leucine; D020689:Exopeptidases; D000626:Aminopeptidases; D007930:Leucine; C012211:ubenimex; C100827:TP 7