Table 2.

Effects of metal cations and protease inhibitor on the activity of APB-AN when incubated for 1 h

Metal ions	Concentration (mmol/L)	Relative activity (%)
Ca2+	1	74.4 ± 2.3
Co2+	1	127.3 ± 6.9
Cu2+	1	7.4 ± 0.8
Fe2+	1	16.5 ± 2.7
Mg2+	1	55.5 ± 3. 6
Mn2+	1	84.2 ± 5.3
Zn2+	1	97.3 ± 3.8
Na2+	100	108.7 ± 2.1
1,10-Phenanthrolinea	1	3.2 ± 0. 5
Bestatin	0.05	12.7 ± 1.3
EDTAa	1	43.1 ± 2.2
E-64	0.05	89.6 ± 4.2
Pepstatin	0.05	94.1 ± 7.4
PMSF	1	98.7 ± 5.6
Puromycin	0.05	4.9 ± 0.8
Control	0	100

The enzyme activity of recombinant APB-AN without the addition of metal cations and protease inhibitors was defined as 100%. The effects of metal cations and protease inhibitors on APB-AN activity were calculated as the mean and standard error of three trials

^aSample incubated for 6 h