Abstract
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 m
m Co(NO
3)
2. In most cases Co
2+ activation decreased
K
m(app)
values and increased
k
cat values, in other cases
k
m(app)
and
k
cat values were increased; for the remainder of the substrates tested
k
m(app)
values and
k
cat values were decreased. In all cases tested the ratios of
(
k
cat
K
m(
app)
)
CO
2+/(
k
cat
K
m(
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 Co
2+ 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; Co
2+ activation of the enzyme affected an appreciable rate of hydrolysis of the latter substrate.