TABLE 2.

Specific activities of wild-type EchA and variants toward pure (R)-styrene oxide and (S)-styrene oxide

Enzymea	Formationb of:				(R)-diol rate vs (S)-diol rate
	(R)-1-phenylethane-1,2-diol		(S)-1-phenylethane-1,2-diol
	Rate (μmol/min/mg)	Fold difference from WT rate	Rate (μmol/min/mg)	Fold difference from WT rate	Ratio	Fold difference from WT rate
Wild-type EchA	1.00 ± 0.12	1.0	3.21 ± 0.30	1.0	0.31	1.0
F108L	1.89	1.9	4.51 ± 0.43	1.4	0.42	1.3
I219Fc	1.43 ± 0.02	1.4	0.93 ± 0.09 (0-10 min)	0.29	1.54	4.9
			0.27 ± 0.03 (10-30 min)	0.08	5.3	1.7
C248I	1.58 ± 0.36	1.6	1.99 ± 0.10	0.55	0.79	2.5
F108L/C248I	1.04 ± 0.06	1.0	1.27 ± 0.10	0.40	0.82	2.6
I219L/C248I	0.93 ± 0.13	0.9	1.18 ± 0.11	0.37	0.78	2.5
F108L/I219L/C2481	2.94 ± 0.27	2.9	1.78 ± 0.23	0.55	1.65	5.3
L190F	2.76 ± 0.71	2.8	8.76 ± 0.62	2.7	0.32	1.0
L190Y	2.18 ± 0.17	2.2	7.39 ± 0.22	2.3	0.29	0.95

^aCrude enzymes were prepared by cell sonication; the EchA concentration from each strain was 50 μg/ml as estimated from SDS-PAGE.

^bThe formation rates of (R)- and (S)-1-phenylethane-1,2-diol were determined via chiral HPLC and were from a linear range.

^cI219F exhibited distinctive two-stage (S)-1-phenylethane-1,2-diol formation, and the rates for these two stages (0 to 10 min and 10 to 30 min) were determined separately.