Purification and characterisation of a vitellogenin derived aminopeptidasefrom rainbow trout eggs

An aminopeptidase specific for N-terminal alanine was isolated from the rai nbow trout (Oncorhynchus mykiss) maturing eggs using a simple procedure. Th e 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 (I)EVNAVKCSMV(10)RDTLTTFNNK(20)KY QIN(25). The sequence is identical with that of the rainbow trout vitelloge nin 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 Na-4-EDTA but it is not inacti vated by 4-(chloromercuri)benzoate, phenylmethanesulfonyl fluoride or pepst atin A.