Table 1.

Kinetic parameters for hydrolysis of Group I paraoxon analogs by rePON1 G2E6

Molecule ID			kcat s−1	KM mM	kcat/KM M−1 s−1	IC50 mM
	R1	R2
1	Et	OEt	2.1 ± 0.2	0.9 ± 0.2	2,300 ± 700
6	Me	OMe	> 0.2	> 1.5	100 ± 10 a
7	Et	OMe	1.5 ± 0.1	0.6 ± 0.2	2,800 ± 800
8	Et	OPr	0.63 ± 0.02	0.4 ± 0.1	1,700 ± 200
9	Et	Oi-Pr	0.14 ± 0.01	0.6 ± 0.1	230 ± 50
10	Pr	OPr	0.07 ± 0.01	0.3 ± 0.1	200 ± 100	weak b
11	i-Pr	Oi-Pr	c	c	c	weak b
12	MeCyp	OMeCyp	weak	weak	weak	d
13	Bu	OBu	c	c	c	d
14	Et	OPentyl	0.18 ± 0.04	1.3 ± 0.7	140 ± 80	weak b
15	Et	OCyclohexyl	c	c	c	0.5 b
16	Et		c	c	c	d

^aSaturation was not possible for this substrate under the experimental conditions; only k_cat/K_M could be determined via a linear fit.

^bAlthough the leaving group is the same as for paraoxon for all Group I compounds, we are able to observe inhibition of paraoxonase activity in substrates with turnover that is much slower than the turnover of paraoxon (1).

^cNo observable activity.

^dNo inhibition was observed.