High level expression and biochemical characterization of an alkaline serine protease from Geobacillus stearothermophilus to prepare antihypertensive whey protein hydrolysate

Table 2 Effect of selective protease inhibitors on the protease activity of GsProS8. Different letters (a-f) on the same column indicated significant (p < 0.05) differences among samples*

Inhibitor	Concentration (mM)	Specific activity (U/mg)	Relative activity (%)
Pepstatin A	0.01	3201.0 ± 49.7^a	89.9
Pepstatin A	0.02	2993.5 ± 52.0^b	84.1
PMSF	1	162.3 ± 20.3^e	4.6
PMSF	4	10.3 ± 2.3^f	0.3
Iodoacetamide	1	3277.0 ± 15.8^a	92.1
Iodoacetamide	4	2901.0 ± 36.2^b	81.5
EDTA	1	2475.7 ± 29.4^c	69.5
EDTA	4	2118.2 ± 6.8^d	59.5

*Enzymatic reaction was carried out using casein as a substrate at 50 °C in 0.05 mol/L MOPS buffer (pH 8.5). Specific activity was shown as mean ± SD (n = 3). Relative activity was expressed as a percentage of the activity in the absence of inhibitors (the control)

ISSN: 1472-6750