Table 2.

Effect of different inhibitors and metal ions on the protease activity

Reagent	Concentration (mM)	Relative activity of protease (%)
		Purified protease	Commercial neutral protease
Control		100	100
PMSF	1.0	27.89 ± 1.55	49.8 ± 2.77
EDTA	1.0	18.85 ± 0.95	34.99 ± 0.06
IAM	1.0	47.03 ± 1.53	92.31 ± 0.21
Pepstatin A	1.0	63.04 ± 2.85	92.33 ± 1.15
KCl	0.2	158.56 ± 3.45	141.17 ± 1.18
NaCl	0.2	115.92 ± 3.67	112.69 ± 1.32
CaCl2	0.2	273.44 ± 3.56	246.02 ± 4.44
SnCl2·2H2O	0.2	174.29 ± 2.56	162.56 ± 3.63
CuSO4·5H2O	0.2	325.99 ± 4.51	303.33 ± 3.29
MgCl2	0.2	57.67 ± 3.44	49.58 ± 3.62
BaCl2·2H2O	0.2	42.13 ± 1.65	30.17 ± 1.42
MnCl2·4H2O	0.2	244.76 ± 3.78	233.85 ± 2.28
ZnCl2	0.2	91.39 ± 3.76	88.66 ± 4.08
Pb(CH3COO)2·3H2O	0.2	123.69 ± 3.84	118.47 ± 4.03
FeSO4·7H2O	0.2	124.76 ± 2.85	122.62 ± 4.7
AlCl3	0.2	153.93 ± 4.77	150.6 ± 2.96

The purified protease activity from Aspergillus oryzae Y1 and commercial neutral protease activity without the addition of metal ions was defined as 100%