Apparent Km values of 2.05 ± 0.09 mg mL−1 and 0.154 ± 0.004 mg mL−1, respectively, were determined. The maximum velocity vmax was calculated to be 346 ± 15 nkat mL−1 with Na–CN and 192.3 ± 5.3 nkat mL−1 with β-casein as a substrate. Taking these kinetic parameters into account, a catalytic efficiency (vmax/Km) of 169 nkat mg−1 can be determined for Na–CN as substrate.