Optimization of Acid Protease Production by Aspergillus niger I1 on Shrimp Peptone Using Statistical Experimental Design

Table 7

Effect of some metal ions and inhibitors on A. niger I1 protease activity.

Chemicals	Concentration (mM)	Relative activity (%)
Control	—	100
Ca^2+	5	100 ± 2
Mg^2+	5	86
Mn^2+	5	85 ± 3
Cu^2+	5	61 ± 4
Ba^2+	5	87
Hg^2+	5	78 ± 2
Na^+	5	93 ± 2
K^+	5	110 ± 3
Zn^2+	5	97
PMSF	5	100
EDTA	5	100
DTNB	5	100
Pepstatin A	1.5×10^−3	0
β-mercaptoethanol	5	100 ± 3