Glutathione-degrading enzymes of microvillus membranes Academic Article uri icon

Overview

MeSH Major

  • Aminopeptidases
  • Cell Membrane
  • Dipeptidases
  • Epididymis
  • Glutathione
  • Jejunum
  • Kidney
  • Microvilli
  • gamma-Glutamyltransferase

abstract

  • Microvillus membranes from rat kidney, jejunum, and epididymis have been purified by the Ca precipitation method. The membranes exhibit enrichment in specific activities of gamma-glutamyl transpeptidase, aminopeptidase M, and a dipeptidase. The latter has been characterized and shown to be the principal activity responsible for the hydrolysis of S derivatives of Cys-Gly (including cystinyl-bis-glycine (Cys-bis-Gly) and 5-hydroxy-6-S-cysteinylglycyl-1-7,9-trans-11,14-cis-eicosatetraenoic acid (leukotriene D4)). A method is described for the simultaneous purification of papain-solubilized forms of the three enzymes from renal microvilli. Dipeptidase (Mr = 105,000) appears to be a zinc metalloprotein composed of two Mr = 50,000 subunits. The enzyme is severalfold more effective in the hydrolysis of dipeptides than aminopeptidase M. Dipeptidase, in contrast to aminopeptidase M, is inhibited by thiol compounds; Cys-Gly, in particular, is a potent inhibitor (Ki = 20 microM). The inhibition of dipeptidase by thiols has been employed to probe the relative significance of dipeptidase and aminopeptidase M in the metabolism of glutathione and its derivatives at the membrane surface.

publication date

  • January 1982

Research

keywords

  • Academic Article

Identity

Language

  • eng

PubMed ID

  • 6122685

Additional Document Info

start page

  • 6322

end page

  • 7

volume

  • 257

number

  • 11