【摘 要】
：
A gene, lacH, encoding lactofen-hydrolyzing esterase was cloned from Brevundimonas sp.LY-2.The gene contained an open reading frame of 921 bp, and a putative signal peptide at the N-terminal was ident
【机 构】
：
Key Laboratory of Agricultural Environmental Microbiology,Ministry of Agriculture,College of Life Sc
【出 处】
：
第十六次全国环境微生物学学术研讨会
论文部分内容阅读
A gene, lacH, encoding lactofen-hydrolyzing esterase was cloned from Brevundimonas sp.LY-2.The gene contained an open reading frame of 921 bp, and a putative signal peptide at the N-terminal was identified with the most likely cleavage site situated between the amino acids Ala 28 and Ala 29, and resulted in a 278 residue mature protein.LacH minus the signal peptide was expressed in Escherichia coli BL21 and purified using Ni-nitrilotriacetic acid affinity chromatography.The purified LacH not only degraded lactofen, but also hydrolyzed p-nitrophenyl esters of various fatty acids, indicating that LacH is an esterase with broad substrates.The optimum pH and temperature of the purified enzyme were 7.0 and 40℃, respectively.The activity of the enzyme was completely inhibited by Hg2+, Zn2+ and the thiol reagent iodoacetamide.Hydrolysis of lactofen enantiomers was observed with enantiomeric selectivity, indicating the enzyme is able to differentiate between the enantiomers.
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