An Aminopeptidase Activity in Bovine Pituitary Secretory Vesicles That Cleaves the N-terminal Arginine From beta-lipotropin60-65

FEBS Lett. 1984 Sep 17;175(1):135-9. doi: 10.1016/0014-5793(84)80586-4.

Abstract

Secretory vesicles isolated from the neural and intermediate lobes of the bovine pituitary contained a membrane-bound aminopeptidase activity which cleaved arginine from beta-LPH60-65 (Arg-Tyr-Gly-Gly-Phe-Met) and Arg-MCA. Neither methionine enkephalin (Tyr-Gly-Gly-Phe-Met) nor Substance P, which has an N-terminal arginine followed by a proline, could serve as substrates for this aminopeptidase activity; nor could cathepsin B-like or chymotrypsin-like enzyme activities be detected in the vesicle preparations. Maximal enzyme activity was at pH 6.0, and the activity was inhibited by EDTA, stimulated by Co2+ and Zn2+, but was unaffected by leupeptin, pepstatin A, phenylmethylsulfonyl fluoride and p-chloromercuribenzenesulfonate, suggesting that the enzyme is a metalloaminopeptidase. The presence of this aminopeptidase activity in secretory vesicles suggests that it may be involved in peptide prohormone processing.

MeSH terms

  • Aminopeptidases / metabolism*
  • Animals
  • Arginine / metabolism
  • Cations, Divalent
  • Cattle
  • Cytoplasmic Granules / enzymology*
  • Edetic Acid / pharmacology
  • Hydrogen-Ion Concentration
  • Kinetics
  • Organ Specificity
  • Peptide Fragments / metabolism*
  • Pituitary Gland / enzymology*
  • Pituitary Gland, Posterior / enzymology
  • Protease Inhibitors / pharmacology
  • Substrate Specificity
  • beta-Lipotropin / metabolism*

Substances

  • Cations, Divalent
  • Peptide Fragments
  • Protease Inhibitors
  • beta-lipotropin (60-65)
  • beta-Lipotropin
  • Arginine
  • Edetic Acid
  • Aminopeptidases