Identification, Expression, and Purification of a Pyrethroidhydrolyzing Carboxylesterase from Mouse Liver Microsomes
Year: 2004
Type: article
Abstract: Carboxylesterases are enzymes that catalyze the hydrolysis of a wide range of ester-containing endogenous and xenobiotic compounds. Although the use of pyrethroids is increasing, the specific enzymes involved in the hydrolysis of these insecticides have yet to be identified. A pyrethroid-hydrolyzing enzyme was partially purified from mouse liver microsomes using a fluorescent reporter similar in structure to cypermethrin (Shan, G., and Hammock, B. D. (2001) Anal. Biochem. 299, 54-62 and Wheelock, C. E., Wheelock, A. M., Zhang, R., Stok, J. E., Morisseau, C., Le Valley, S. E., Green, C. E., and Hammock, B. D. (2003) Anal. Biochem. 315, 208-222) and subsequently identified as a carboxylesterase (NCBI accession number BAC36707). The expressed sequence tag was then cloned, expressed in baculovirus, and purified to homogeneity. Kinetic constants for a large number of both type I and type II pyrethroid or pyrethroid-like substrates were determined. This esterase possesses similar kinetic constants for cypermethrin and its fluorescent-surrogate (k(cat) = 0.12 +/- 0.03 versus 0.11 +/- 0.01 s(-1)). Compared with their cis- counterparts, trans-permethrin and cypermethrin were hydrolyzed 22- and 4-fold faster, respectively. Of the four fenvalerate isomers the (2R)(alphaR)-isomer was hydrolyzed at least 1 order of magnitude faster than any other isomer. However, it is unlikely that this enzyme accounts for the total pyrethroid hydrolysis in the microsomes because both isoelectrofocusing and native PAGE indicate the presence of a second region of cypermethrin-metabolizing enzymes. A second carboxylesterase gene (NCBI accession number NM_133960), isolated during a cDNA mouse liver library screening, was also found to hydrolyze pyrethroids. Both these enzymes could be used as preliminary tools in establishing the relative toxicity of new pyrethroids.
Source: Journal of Biological Chemistry
Authors: Jeanette E. Stok, Huazhang Huang, Paul D. Jones, Craig E. Wheelock, Christophe Morisseau, Bruce D. Hammock
Institution: University of California, Davis
Language: English
Subfield: Plant Science
Domain: Life Sciences
Open Access status: hybrid
Estimated APC paid: $3,430
Awards: Pre &Postdoctoral Training in Nutrition, NIEHS Center for Health Effects of Agrochemicals, Control of Urban and Peri-urban Culex Mosquitoes, Biomarkers of Exposure to Hazardous Substances, G2556748894, G3068097868, G3498535170, HYDROLYTIC ENZYMES IN THE METABOLISM OF TOXINS, G465352144, G5096026339, G622880495, G9000000914, G9000114809
OpenAlex ID: W2107115483