Functional Cloning and Expression of a Novel Endo-α-1,5-L-Arabinanase from a Metagenomic Library

Author(s): Dominic W.S. Wong, Victor J. Chan, Amanda A. McCormack.

Journal Name: Protein & Peptide Letters

Volume 16 , Issue 12 , 2009

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Abstract:

A novel endo-α-L-arabinanase gene (arn2) was isolated, and expressed in E. coli in active form. The recombinant enzyme (ARN2) had optimum activity at pH 6.0 and 45-50oC with stability between pH 5.0-8.0 and at temperatures up to 40oC. The recombinant ARN2 catalyzed internal cleavage of α-1,5 glycosidic bonds of CM-arabinan, debranched arabinan, linear arabinan, and sugar beet (native) arabinan at rates of decreasing order, and was inactive on wheat arabinoxylan and p-nitrophenyl- α-L-arabinofuranoside. Kinetic analysis showed that branching in the arabinan did not significantly affect the apparent Km values, and the difference in the reaction rates was likely due to the chemical step after substrate binding. The enzyme hydrolyzed arabino-oligosaccharides of DP 6 to smaller oligomers and mostly arabinotriose. Natural and modified arabinans were cleaved to oligomers of various chain lengths, which were progressively hydrolyzed to yield arabinotriose. The pattern of degradation revealed an endo-acting mechanism with arabinotriose as the end product.

Keywords: Arabinanase, endo-arabinanase, pectinase, arabinan-degrading enzyme

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Article Details

VOLUME: 16
ISSUE: 12
Year: 2009
Page: [1435 - 1441]
Pages: 7
DOI: 10.2174/092986609789839313
Price: $58

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