TABLE 5.

Kinetic parameters of WT Zg-VIPO1 and mutants, determined by thymol blue colorimetric assay

Enzyme	KmI− (mM)a	% of WT value	kcatI− (s−1)a	% of WT value	kcatI−/KmI− (s−1 mM−1)	% of WT value
Zg-VIPO1 (WT)	0.22 ± 0.01	100	1.98 ± 0.05	100	9.00	100
Tyr263Ala mutant	0.44 ± 0.17	200	3.53 ± 0.25	178	8.02	89
Tyr263Phe mutant	0.79 ± 0.07	359	2.67 ± 0.08	135	3.38	38
Tyr263Ser mutant	1.58 ± 0.30	718	13.97 ± 2.43	706	8.84	98
Cys320Ser mutant	0.91 ± 0.28	414	2.76 ± 0.87	139	3.03	34
Trp321Arg mutant	0.39 ± 0.11	177	1.78 ± 0.22	90	4.56	51
Asp322Lys mutant	1.38 ± 0.43	627	3.86 ± 1.1	195	2.80	31
Asp322Tyr mutant	0.03 ± 0.03	14	0.0007 ± 0.0006	0.04	0.02	0.3
Phe353His mutant	2.63 ± 0.53	1,195	53.27 ± 10.77	2,690	20.25	225
Ser358Ala mutant	0.19 ± 0.06	86	2.19 ± 0.07	111	11.53	128
His360Ala mutant	0.02 ± 0.01	9	0.01 ± 0.0003	0.5	0.50	6
His360Ser mutant	0.05 ± 0.08	23	0.002 ± 0.001	0.1	0.04	0.4
Arg410Ala mutant	3.45 ± 1.07	1,568	0.03 ± 0.01	1.5	0.01	0.1

^aValues are means ± SD.