Publications

• Cloning of a novel pyrethroid-hydrolyzing carboxylesterase gene from Sphingobium sp. strain JZ-1 and characterization of the gene product.

  Wang B.Z., Guo P., Hang B.J., Li L., He J., Li S.P.

  A novel esterase gene, pytH, encoding a pyrethroid-hydrolyzing carboxylesterase was cloned from Sphingobium sp. strain JZ-1. The gene contained an open reading frame of 840 bp. Sequence identity searches revealed that the deduced enzyme shared the highest similarity with many alpha/beta-hydrolase ... >> More

  A novel esterase gene, pytH, encoding a pyrethroid-hydrolyzing carboxylesterase was cloned from Sphingobium sp. strain JZ-1. The gene contained an open reading frame of 840 bp. Sequence identity searches revealed that the deduced enzyme shared the highest similarity with many alpha/beta-hydrolase fold proteins (20 to 24% identities). PytH was expressed in Escherichia coli BL21 and purified using Ni-nitrilotriacetic acid affinity chromatography. It was a monomeric structure with a molecular mass of approximately 31 kDa and a pI of 4.85. PytH was able to transform p-nitrophenyl esters of short-chain fatty acids and a wide range of pyrethroid pesticides, and isomer selectivity was not observed. No cofactors were required for enzyme activity. << Less

  Appl. Environ. Microbiol. 75:5496-5500(2009) [PubMed] [EuropePMC]

• Identification, expression, and purification of a pyrethroid-hydrolyzing carboxylesterase from mouse liver microsomes.

  Stok J.E., Huang H., Jones P.D., Wheelock C.E., Morisseau C., Hammock B.D.

  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-hydrolyzi ... >> More

  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. << Less

  J. Biol. Chem. 279:29863-29869(2004) [PubMed] [EuropePMC]

• Purification and preliminary characterization of permethrinase from a pyrethroid-transforming strain of Bacillus cereus.

  Maloney S.E., Maule A., Smith A.R.

  Bacillus cereus SM3 was isolated on a mineral salts medium with Tween 80 as the primary carbon source. It was able to hydrolyze second- and third-generation pyrethroids, thereby generating noninsecticidal products. The enzyme responsible for this hydrolytic reaction was named permethrinase for thi ... >> More

  Bacillus cereus SM3 was isolated on a mineral salts medium with Tween 80 as the primary carbon source. It was able to hydrolyze second- and third-generation pyrethroids, thereby generating noninsecticidal products. The enzyme responsible for this hydrolytic reaction was named permethrinase for this study. This is the first instance in which pyrethroid detoxification has been achieved with a cell-free microbial enzyme system. Permethrinase was purified by ion-exchange chromatography and gel filtration chromatography. The molecular mass of native permethrinase was 61 +/-3 kDa, as estimated by Sephadex G-100 gel filtration. This novel microbial esterase seems to be a carboxylesterase. Permethrinase activity had an optimum pH of 7.5 and a temperature optimum of 37 degrees C. No cofactors or coenzymes were required for permethrinase activity. The enzyme may be a serine esterase, as it seems to be sensitive to the organophosphorus compound tetraethylpyrophosphate at concentrations in the micromolar range. Addition of dithiothreitol afforded permethrinase protection against the inhibitory effects of the sulfydryl agents p-chloromercuribenzoate and N-ethylmaleimide. The enzyme was stable over a range of temperatures. Cell extracts of strain SM3 also contained another esterase, which was active towards beta-naphthylacetate, but this enzyme was distinct from permethrinase. << Less

  Appl Environ Microbiol 59:2007-2013(1993) [PubMed] [EuropePMC]

• Molecular cloning, purification, and biochemical characterization of a novel pyrethroid-hydrolyzing esterase from Klebsiella sp. strain ZD112.

  Wu P.C., Liu Y.H., Wang Z.Y., Zhang X.Y., Li H., Liang W.Q., Luo N., Hu J.M., Lu J.Q., Luan T.G., Cao L.X.

  The gene encoding pyrethroid-hydrolyzing esterase (EstP) from Klebsiella sp. strain ZD112 was cloned into Escherichia coli and sequenced. A sequence analysis of the DNA responsible for the estP gene revealed an open reading frame of 1914 bp encoding for a protein of 637 amino acid residues. No sim ... >> More

  The gene encoding pyrethroid-hydrolyzing esterase (EstP) from Klebsiella sp. strain ZD112 was cloned into Escherichia coli and sequenced. A sequence analysis of the DNA responsible for the estP gene revealed an open reading frame of 1914 bp encoding for a protein of 637 amino acid residues. No similarities were found by a database homology search using the nucleotide and deduced amino acid sequences of the esterases and lipases. EstP was heterologously expressed in E. coli and purified. The molecular mass of the native enzyme was approximately 73 kDa as determined by gel filtration. The results of sodium dodecyl sulfate-polyacrylamide gel electrophoresis and the deduced amino acid sequence of EstP indicated molecular masses of 73 and 73.5 kDa, respectively, suggesting that EstP is a monomer. The purified EstP not only degraded many pyrethroid pesticides and the organophosphorus insecticide malathion, but also hydrolyzed rho-nitrophenyl esters of various fatty acids, indicating that EstP is an esterase with broad substrates. The K(m) for trans- and cis-permethrin and k(cat)/K(m) values indicate that EstP hydrolyzes both these substrates with higher efficiency than the carboxylesterases from resistant insects and mammals. The catalytic activity of EstP was strongly inhibited by Hg2+, Ag+, and rho-chloromercuribenzoate, whereas a less pronounced effect (3-8% inhibition) was observed in the presence of divalent cations, the chelating agent EDTA, and phenanthroline. << Less

  J. Agric. Food Chem. 54:836-842(2006) [PubMed] [EuropePMC]

• Tandem aldol-allylation and aldol-aldol reactions with ketone-derived enolsilanes: highly diastereoselective single-step synthesis of complex tertiary carbinols.

  Wang X., Meng Q., Perl N.R., Xu Y., Leighton J.L.

  A new tandem aldol-allylation reaction employing ketone-derived enolates has been developed that leads to the rapid, diastereoselective synthesis of tertiary carbinol containing fragments with relevance to polyketide natural product synthesis. In addition, the use of ketone-derived enolates has le ... >> More

  A new tandem aldol-allylation reaction employing ketone-derived enolates has been developed that leads to the rapid, diastereoselective synthesis of tertiary carbinol containing fragments with relevance to polyketide natural product synthesis. In addition, the use of ketone-derived enolates has led to the development of a new tandem aldol-aldol reaction. << Less

  J Am Chem Soc 127:12806-12807(2005) [PubMed] [EuropePMC]

• Purification and characterization of a novel pyrethroid hydrolase from Aspergillus niger ZD11.

  Liang W.Q., Wang Z.Y., Li H., Wu P.C., Hu J.M., Luo N., Cao L.X., Liu Y.H.

  The pyrethroid pesticides residues on foods and environmental contamination are a public safety concern. Pretreatment with pyrethroid hydrolase has the potential to alleviate the conditions. For this purpose, a fungus capable of using pyrethroid pesticides as a sole carbon source was isolated from ... >> More

  The pyrethroid pesticides residues on foods and environmental contamination are a public safety concern. Pretreatment with pyrethroid hydrolase has the potential to alleviate the conditions. For this purpose, a fungus capable of using pyrethroid pesticides as a sole carbon source was isolated from the soil and characterized as Aspergillus niger ZD11. A novel pyrethroid hydrolase from cell extract was purified 41.5-fold to apparent homogeneity with 12.6% overall recovery. It is a monomeric structure with a molecular mass of 56 kDa, a pI of 5.4, and the enzyme activity was optimal at 45 degrees C and pH 6.5. The activities were strongly inhibited by Hg(2+), Ag(+), and rho-chloromercuribenzoate, whereas less pronounced effects (5-10% inhibition) were observed in the presence of the remaining divalent cations, the chelating agent EDTA and phenanthroline. The purified enzyme hydrolyzed various insecticides with similar carboxylester. trans-Permethrin is the preferred substrate. << Less

  J Agric Food Chem 53:7415-7420(2005) [PubMed] [EuropePMC]