BACILLUS-SUBTILIS AMINOPEPTIDASE - SPECIFICITY TOWARD AMINO ACYL-BETA-NAPHTHYLAMIDES

The kinetic parameters for the hydrolyses of different l-α-amino acid-β-naphthylamides by Bacillus subtilis aminopeptidase have been measured for the native enzyme and for the enzyme activated in 5 mm Co(NO3)2. In most cases Co2+ activation decreased Km(app) values and increased kcat values, in other cases km(app) and kcat values were increased; for the remainder of the substrates tested km(app) values and kcat values were decreased. In all cases tested the ratios of ( kcat Km(app))CO2+/( kcat Km(app)nativ) were increased (2- to 108-fold). For the native enzyme the order of specificity toward the l-amino acid-β-naphthylamides was Arg > Met > Trp > Lys > Leu and for the Co2+ activated enzyme the order of specificity was Lys > Arg > Met > Trp > Leu. The native enzyme hydrolyzed Pro-β-naphthylamide, but not α-Glu-β-naphthylamide; Co2+ activation of the enzyme affected an appreciable rate of hydrolysis of the latter substrate. © 1979.