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Functional Proteomic Analysis of Rice Bran Esterases/Lipases and Characterization of a Novel Recombinant Esterase.
MedLine Citation:
PMID:  21322560     Owner:  NLM     Status:  Publisher    
Abstract/OtherAbstract:
An esterase from rice ( Oryza sativa ) bran was identified on two-dimensional gel using 4-methylumbelliferyl butyrate as a substrate. The esterase cDNA (870 bp) encoded a 289 amino acid protein (designated OsEST-b) and was expressed in Escherichia coli . The molecular weight of recombinant OsEST-b (rOsEST-b) was 27 kDa, as measured by sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Biochemical characterization demonstrated that rOsEST-b was active over a broad temperature range (optimum at 60 °C) and preferred alkaline conditions (optimum at pH 9.0). The rOsEST-b showed maximum activity toward p-nitrophenyl butyrate (C(4)) among various p-nitrophenyl esters (C(4)-C(18)), indicating that rOsEST-b is an esterase for short-chain fatty acids. The kinetic parameters under optimal conditions were K(m) = 27.03 μM, k(cat) = 49 s(-1), and k(cat)/K(m) = 1.81 s(-1) μM(-1). The activity of rOsEST-b was not influenced by ethylenediaminetetraacetic acid, suggesting that it is not a metalloenzyme. The amino acid sequence analysis revealed that OsEST-b had a conserved pentapeptide esterase/lipase motif but that the essential active site serine (GXSXG) was replaced by cysteine (C). These results suggest that OsEST-b is distinct from traditional esterases/lipases and is a novel lipolytic enzyme in rice bran.
Authors:
Hsu-Han Chuang; Po-Ting Chen; Wun-Nai Wang; Yu-Ting Chen; Jei-Fu Shaw
Publication Detail:
Type:  JOURNAL ARTICLE     Date:  2011-2-15
Journal Detail:
Title:  Journal of agricultural and food chemistry     Volume:  -     ISSN:  1520-5118     ISO Abbreviation:  -     Publication Date:  2011 Feb 
Date Detail:
Created Date:  2011-2-16     Completed Date:  -     Revised Date:  -    
Medline Journal Info:
Nlm Unique ID:  0374755     Medline TA:  J Agric Food Chem     Country:  -    
Other Details:
Languages:  ENG     Pagination:  -     Citation Subset:  -    
Affiliation:
Department of Food Science and Biotechnology, National Chung Hsing University , Taichung 402, Taiwan.
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