Table 1.

.Specific Activity of Mammalian and Human Liver Carboxylesterases toward Pyrethroid-like Fluorescent Substrates^a

substrates	porcineb	rabbitb	humanc hCE1	moused NM_133960	moused BAC36707
		Cypermethrin Analogues
1R cis, αR	2.35(0.17)	5.67(0.49)	0.60(0.02)	3.94(0.37)	19.74(2.18)
1S cis, αR	2.45(0.22)	5.71(0.83)	0.36(0.13)	7.44(0.66)	8.44(0.37)
1R trans, αR	26.8(1.8)e	12.2(1.4)	16.0(1.60)e	7.63 (0.27)	26.2(2.8)e
1S trans, αR	51.0(2.6)e	37.5(2.6)e	21.3(2.2)e	85.1(3.2)e	281(24)e
1R cis, αS	33.4(4.5)e	7.41(0.04)	0.64(0.06)	20.3(0.1)e	2.28(0.31)
1S cis, αS	6.62(0.46)	3.73(0.37)	0.66(0.05)	8.69(0.85)	6.69(1.06)
1R trans, αS	42.4(3.8)e	55.6(7.5)e	55.2(3.1)e	7.34(0.76)	14.6(1.2)e
1S trans, αS	61.2(1.8)e	83.4(11.3)e	14.7(1.3)e	155(2)e	327(25)e
		Fenvalerate Analogues
2R,αR	1.62(0.07)	17.1(1.0)e	0.38(0.01)e	10.3(0.4)e	40.3(2.6)e
2R, αS	8.34(0.35)	15.0(0.4)e	0.58(0.10)e	15.2(0.3)e	54.2(3.4)e
2S,αR	4.31 (0.32)	0.25(0.04)	NDf	0.63(0.05)	NDf
2S, αS	2.66(0.20)	4.61(0.04)	0.04(0.03)	0.79(0.11)	NDf

^aValues stand for mean activities ((nmol/min)/mg protein, SD in parentheses) based on triplicate assays.

^bPorcine and rabbit liver carboxylesterases are commercial from Sigma-Aldrich; they were mixtures of multiple isozymes.

^cHuman (hCE1) carboxy-lesterase was expressed in insect cells with a recombinant bacu-lovirus expression system, then recombinant hCE1 was sequentially purified by anion-exchange chromatography, preparative electrophoresis, and gel-filtration chromatography.

^dMouse: two recombinant mouse liver carboxylesterase (NCBI accession nos. NM_133960 and BAC36707) were recently purified (12), and data were presented in ref 13.

^ePreference was considered if one stereoisomer is hydrolyzed by one carboxylesterase over 5 times faster than the least favored isomer in a single series.

^fND = not detectable under the same protein as other stereoisomers.