title: Purification and characterization of an esterase conferring resistance to fenitrothion in Oryzaephilus surinamensis (L.) (insecta, coleoptera, silvanidae).
abstract: Esterases from a fenitrothion-resistant strain (VOSF) of the saw-toothed grain beetle, Oryzaephilus surinamensis (L.), are presumed to play a role in conferring resistance to malathion, fenitrothion, and chlorpyrifos-methyl. Colorimetric assays showed a significant positive correlation between increased resistance to fenitrothion in strains of O. surinamensis examined and elevated esterase hydrolytic activity to substrates of p-nitrophenyl acetate, alpha-naphthyl acetate, and beta-naphthyl acetate. Esterase zymograms showed different banding patterns between VOSF and an insecticide-susceptible strain, VOS48. A major esterase in the VOSF strain, not detected in VOS48, was purified and characterized by chromatographic and electrophoretic techniques. On the basis of SDS-polyacrylamide gel eletrophoresis, the molecular mass of the purified esterase from VOSF was 130 kDa and consisted of two 65 kDa subunits. Additional properties of this enzyme are discussed.
authors.affiliation: Plant Protection Research Unit, Western Regional Research Center, Agricultural Research Service, U.S. Department of Agriculture, 800 Buchanan Street, Albany, California 94710, USA.
authors.forename: S E
authors.initials: SE
authors.lastname: Lee
authors.forename: E M
authors.initials: EM
authors.lastname: Lees
authors.forename: B C
authors.initials: BC
authors.lastname: Campbell
mesh_terms: D000818:Animals; D001517:Coleoptera / Q000201:enzymology*; D004591:Electrophoresis, Polyacrylamide Gel; D004950:Esterases / Q000737:chemistry / Q000302:isolation & purification* / Q000378:metabolism; D005278:Fenitrothion / Q000633:toxicity*; D007305:Insecticide Resistance; D007306:Insecticides / Q000633:toxicity*; D007527:Isoenzymes / Q000737:chemistry / Q000302:isolation & purification; D007700:Kinetics; D008970:Molecular Weight
chemical_list: D007306:Insecticides; D007527:Isoenzymes; D004950:Esterases; D005278:Fenitrothion