Table 1. Kinetic parameters of wild-type, N385L, and I387A BSAPs^a.

Substrate	BSAP variant	kcat (s−1)	kcat relative to WT	Km (mM)	Km relative to WT	kcat/ Km (mM−1 s−1)	kcat/ Km relative to WT
Leu-pNA	WTb	70.66 ± 3.58	1	2.52 ± 0.11	1	28.1	1
	N385L	52.58 ± 2.49	0.74	1.78 ± 0.09	0.73	29.5	1.01
	I387A	11.65 ± 0.93	0.17	12.27 ± 0.98	4.96	0.95	0.03
Lys-pNA	WT	10.71 ± 0.54	1	4.12 ± 0.24	1	2.60	1
	N385L	26.27 ± 1.46	2.45	3.86 ± 0.19	0.94	6.81	2.61
	I387A	6.82 ± 0.51	0.62	7.56 ± 0.41	1.82	0.91	0.34
Phe-pNA	WT	NDc	ND	ND	ND	ND	ND
	N385L	ND	ND	ND	ND	ND	ND
	I387A	7.54 ± 0.35	ND	4.08 ± 0.23	ND	1.85	ND

^aK_m and k_cat values were calculated by nonlinear regression analysis. The values are means ± standard deviations of three independent experiments; ^bWT, wild-type; ^cND, not detected.