2dqx

From Proteopedia

Revision as of 13:20, 23 January 2008

mutant beta-amylase (W55R) from soy bean

Overview

Beta-amylase (EC 3.2.1.2) is starch-hydrolyzing exo-type enzyme that can, catalyze the successive liberation of beta-maltose from the nonreducing, ends of alpha-1,4-linked glucopyranosyl polymers. There is a well-known, phenomenon called multiple or repetitive attack where the enzyme releases, several maltose molecules in a single enzyme-substrate complex. In order, to understand it further, we examined the beta-amylase-catalyzed reaction, using maltooligosaccharides. The Monte Carlo method was applied for, simulation of the beta-amylase-catalyzed reaction including the multiple, attack mechanism. Through site-directed mutagenesis, we have successfully, prepared a mutant enzyme which may be simulated as a multiple attack, action reduced one with retaining significant hydrolytic activity. From, the results of X-ray structure analysis of the mutant enzyme, it was, clarified that one carboxyl residue plays a very important role in the, multiple attack. The multiple attack action needs the force of enzyme, sliding on the substrate. In addition, it is important for the multiple, attack that the enzyme and substrate have the characteristics of a stable, productive substrate-enzyme complex through a hydrogen bond between the, nonreducing end of the substrate and the carboxyl residue of the enzyme.

About this Structure

2DQX is a Single protein structure of sequence from Glycine max. Active as Beta-amylase, with EC number 3.2.1.2 Full crystallographic information is available from OCA.

Reference

Kinetic and structural analysis of enzyme sliding on a substrate: multiple attack in beta-amylase., Ishikawa K, Nakatani H, Katsuya Y, Fukazawa C, Biochemistry. 2007 Jan 23;46(3):792-8. PMID:17223700

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