Identification and characterization of a novel cold-adapted esterase from a metagenomic library of mountain soil |
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Authors: | Kyong-Cheol Ko Soon-Ok Rim Yunjon Han Bong Seok Shin Geun-Joong Kim Jong Hyun Choi Jae Jun Song |
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Institution: | (1) Microbe-based Fusion Technology Research Center, Korea Research Institute of Bioscience and Biotechnology (KRIBB), 1404 Sinjeong-dong, Jeongeup, Jeonbuk, 580-185, Republic of Korea;(2) Department of Biological Sciences, College of Natural Sciences, Chonnam National University, 300 Yong-Bong Dong, Buk-Gu, Gwangju, 500-757, Republic of Korea; |
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Abstract: | A novel lipolytic enzyme was isolated from a metagenomic library after demonstration of lipolytic activity on an LB agar plate
containing 1% (w/v) tributyrin. A novel esterase gene (estIM1), encoding a lipolytic enzyme (EstIM1), was cloned using a shotgun method from a pFosEstIM1 clone of the metagenomic library,
and the enzyme was characterized. The estIM1 gene had an open reading frame (ORF) of 936 base pairs and encoded a protein of 311 amino acids with a molecular mass 34 kDa
and a pI value of 4.32. The deduced amino acid sequence was 62% identical to that of an esterase from an uncultured bacterium (ABQ11271).
The amino acid sequence indicated that EstIM1 was a member of the family IV of lipolytic enzymes, all of which contain a GDSAG
motif shared with similar enzymes of lactic acid microorganisms. EstIM1 was active over a temperature range of 1–50°C, at
alkaline pH. The activation energy for hydrolysis of p-nitrophenyl propionate was 1.04 kcal/mol, within a temperature range of 1–40°C. The activity of EstIM1 was about 60% of maximal
even at 1°C, suggesting that EstIM1 is efficiently cold-adapted. Further characterization of this cold-adapted enzyme indicated
that the esterase may be very valuable in industrial applications. |
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