Catalytic performances of the esterase pnbA-BS and its variants in the saturation mutagenesis of the residue A400^a.

Enzyme	e.e.p (%)	Conversion (%)	E
A400P	97.1 ± 0.4	46.8 ± 1.0	466.6
A400K	94.8 ± 1.2	46.6 ± 0.9	56.8
A400Q	95.7 ± 1.6	11.8 ± 0.2	52.2
A400R	93.7 ± 2.8	25.7 ± 1.5	42.2
A400H	91.4 ± 0.6	46.0 ± 1.3	48.3
A400M	89.3 ± 2.3	7.9 ± 1.4	38.6
A400L	88.9 ± 0.9	47.7 ± 0.8	36.8
A400E	82.6 ± 1.6	45.9 ± 1.4	19.5
A400T	65.6 ± 1.2	58.7 ± 2.4	15.4
A400I	62.9 ± 1.3	59.6 ± 2.9	14.2
A400N	31.6 ± 0.6	74.3 ± 1.9	5.3
A400F	20.1 ± 0.8	78.8 ± 0.4	2.9
A400D	11.3 ± 1.0	86.6 ± 2.7	2.2
A400V	9.8 ± 0.6	88.7 ± 2.3	2.2
A400C	6.7 ± 0.4	89.1 ± 1.5	1.7
A400S	3.2 ± 0.3	88.8 ± 1.7	1.2
A400G	1.8 ± 0.7	98.0 ± 2.6	1.9
pnbA-BS	0.4 ± 0.5	90.5 ± 3.3	1.0
A400Y		No activity
A400W		No activity

^aThe reaction mixture (10 ml) contained 100 mM d, l-menthyl acetate, 50 g l⁻¹ wet cells expressing pnbA-BS or its variant, 10% (v/v) ethanol, and 100 mM PBS buffer solution (pH 7.0). The reaction was conducted in an orbital shaker (600 rpm, 30 °C) for 6 h meanwhile constant pH was maintained by the titration of 1 M NaOH. Data present mean values ± SD from three independent experiments.