TABLE 1.

Kinetics of XR mutants^a

Enzymeb	Cofactor	kcat (min−1)	KmAc (μM)	KmBd (mM)	KiAe (μM)	Rself	Reference
S. stipitis WT	NADPH	63 × 101	2.5	47	−g	−	44
	NADH	42 × 101	31	32	−
Candida tenius WT	NADPH	78 × 101	3.0	96	1.0	0.03	32
	NADH	66 × 101	38	142	19
S. stipitis WT	NADPH	0.30h	1.0	62	1.4	0.04	2
	NADH	0.21h	29	59	26
C. tenius R276H	NADPH	90 × 101	4.0	107	3.0	0.24	32
	NADH	13 × 102	15	94	20
S. stipitis R276H	NADPH	16	1.7	53	−	−	44
	NADH	41 × 101	17	46	−
C. tenius N272D	NADPH	22 × 102	17	170	21	0.23	32
	NADH	84 × 101	26	99	60
S. stipitis K270R	NADPH	2.1h	26	468	23	0.59	2
	NADH	0.96h	63	145	57
C. tenius K270R	NADPH	16 × 102	5.0	350	3.0	1.5	32
	NADH	48 × 101	21	54	4.0
S. stipitis K270R/N272D	NADPH	19 × 102	2810	350	−	−	44
	NADH	71 × 101	138	68	−
C. tenius K270R/N272D	NADPH	38 × 102	128	722	64	2.7	32
	NADH	72 × 101	41	106	30

^aUncertainties of values are not reported, since the manner of calculation differed among investigations.

^bEnzymes are listed in the general order of increasing NADH specificity, R_sel. For the sake of comparison, amino acid residues are numbered in relation to the S. stipitis XR. WT, wild type.

^cA is the cofactor NADH or NADPH; K_mA is the cofactor affinity constant.

^dB is the substrate xylose; K_mB is the substrate affinity constant.

^eA is the cofactor NADH or NADPH; K_iA is the cofactor dissociation constant.

^fThe selectivity ratio, R_sel, is given by [V_max/K_iAK_mB]_NADH/[V_max/K_iAK_mB]_NADPH. V_max is the maximum reaction rate.

^g−, missing data.

^hV_max (U/mg protein) was determined instead of k_cat.