Purification and Characterisation of a Vitellogenin Derived Aminopeptidase from Rainbow Trout Eggs

Abstract

An aminopeptidase specific for N-terminal alanine was isolated from the rainbow trout (Oncorhynchus mykiss) maturing eggs using a simple procedure. The enzyme is composed of two identical units each of MW 16 000, separable by disulfide reduction. The enzyme has a high content of acid amino acids and its N-terminal sequence is the following 1EVNAVKCSMV10RDTLTTFNNK20KYQIN25. The sequence is identical with that of the rainbow trout vitellogenin precursor beginning with the amino acid in position 1 385. No peptidase activity has been so far observed in proteins derived from this precursor. The enzyme activity is partially blocked by Na4-EDTA but it is not inactivated by 4-(chloromercuri)benzoate, phenylmethanesulfonyl fluoride or pepstatin A.

Various peptides as substrates for aminopeptidases from salmon eggs during embryogenesis

“…Study of the role of peptidases in the development of eggs in different fishes showed that enzymes cleaving Arg, Leu, Ala, Cys, and Phe p-nitroanilides exhibited the highest activity in tench and sheatfish eggs incubation medium, while enzymes cleaving Bzl-L-Arg-pNA, L-Pro-pNA, N-Glutaryl-L-Phe-pNA, and Z-Gly-Pro-pNA exhibited lower activity [2,4]. Activities of certain aminopeptidases (AP) gradually increase during maturation of salmon eggs and significantly increase before hatching [3].…”