Alanyl aminopeptidase of bovine seminal vesicle secretion

Multiple forms of an aminopeptidase hydrolysing L-alanine- and various other amino acid-beta-naphthylamides in bovine seminal vesicle secretion were studied after fractionation on gel filtration, anion exchange chromatography and chromatofocusing. Two forms of the enzyme were found in all these fractionations: one with a high molecular weight was aggregated or particle-bound and the other had a molecular weight of about 237,000. The high-molecular-weight form dissociated with Triton X-100 via an intermediate into the basic enzyme form with concurrent change in the pI and anionic sites. The basic form of the enzyme differed from the high-molecular-weight forms in substrate preference, response to some modifiers, thermal stability and kinetic constants.