Activity of Purified Rat Liver Carboxylesterase with Carbalkoxy 
Homologs of Malathion 
Kn SE V max + SE Relative enzy- 
(nM) uM/mg/min matic half-life 
0.695(K_/V__) 
m max’ _ 
Carbomethoxy 0.506 + 0.075 0.52 + 0.04 0.676 
Carbethoxy 6179 = 10.024 Ly S206 712 .069 
Carb-n-propoxy .068 * 0.018 2.46 + 0.26 JO19 
Carb-i-propoxy .040 + 0.007 0.28 * 0.02 099 
Carb-n-butoxy W224 % 00005 2.97 + 0.24 005 
Biomolecular Reaction Constants of Carbalkoxy Homologs of Malathion 
Ky x 104 (m71 min!) 
AcCH Serum | Liver 
esterase cholinesterase carboxylesterase 
Carbomethoxy 6,312 0. 75 1.18 
Carboethoxy 25g 1a OY, bw70 
Carb-n-propoxy L#8 Li e2 8.26 
Carb -i-propoxy 0.90 3.8 3324 
Carb-n-butoxy L./8 32403 37.4 
(332) 
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