A novel esterase from a marine mud metagenomic library for biocatalytic synthesis of short-chain flavor esters

Table 4 Effects of organic solvents on EST4 activity

Organic solvents	log P ^a	Residual activity (%)^b at concentration (%, v/v) of
Organic solvents	log P ^a	20	50	100
Control	–	100.0 ± 2.1	100.0 ± 3.8	100.0 ± 0.5
DMSO	−1.3	82.8 ± 1.7	61.7 ± 8.6	0.6 ± 1.5
DMF	−1.0	92.1 ± 2.5	19.4 ± 4.2	5.8 ± 2.0
Methanol	−0.76	90.6 ± 9.4	23.2 ± 1.8	1.3 ± 3.2
Ethanol	−0.24	102.0 ± 7.7	0.5 ± 2.4	4.9 ± 2.1
Acetone	−0.23	53.1 ± 6.4	ND^c	85.2 ± 1.3
Acetonitrile	−0.15	96.2 ± 2.7	7.8 ± 1.4	89.0 ± 4.3
Isopropanol	0.1	81.3 ± 7.9	ND	97.0 ± 0.9
Benzene	2.0	37.9 ± 3.3	76.1 ± 4.7	92.8 ± 4.3
Toluene	2.5	63.5 ± 1.6	88.1 ± 4.0	90.1 ± 0.5
Cyclohexane	3.2	80.1 ± 2.7	92.7 ± 5.9	99.7 ± 1.8
n-hexane	3.5	53.1 ± 4.6	95.3 ± 10.6	98.6 ± 0.5
n-heptane	4.0	66.1 ± 2.8	96.9 ± 5.6	97.6 ± 1.3
Isooctane	4.5	85.5 ± 5.4	90.0 ± 10.9	98.4 ± 1.0

^alog P value is the partition coefficient of an organic solvent between water and n-octanol phases
^bAfter incubating EST4 for 12 h in different organic solvents, the residual enzymatic activity was measured in 100 mM Tris–HCl buffer (pH 8.0) at 30 °C using p-NP butyrate as the test substrate. An enzyme sample incubated in buffer only was used as the measure of 100 % activity
^c ND not detectable

ISSN: 1475-2859