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GrainGenes Reference Report: PMB-25-141

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Reference	PMB-25-141
Title	Protein engineering in the alpha-amylase family: catalytic mechanism, substrate specificity, and stability
Journal	Plant Molecular Biology
Year	1994
Volume	25
Pages	141-157
Author	Svensson B
Abstract	Most starch hydrolases and related enzymes belong to the alpha-amylase family which contains a characteristic catalytic (B/alpha)8-barrel domain Currently known primary structures that have sequence similarities represent 18 different specificities, including starch branching enzyme Crystal structures have been reported in three of these enzyme classes: the alpha-amylases, the cyclodextrin glucanotransferases, and the oligo-1,6-glucosidases Throughout the alpha-amylase family, only eight amino acid residues are invariant, seven at the active site and a glycine in a short turn However, comparison of three-dimensional models with a multiple sequence alignment suggests that the diversity in specificity arises by variation in substrate binding at the beta to alpha loops. Designed mutations thus have enhanced transferase activity and altered the oligosaccharide product patterns of alpha-amylases, changed the distribution of alpha-, beta- and gamma-cyclodextrin production by cyclodextrin glucanotransferases, and shifted the relative alpha-1,4:alpha-1,6 dual-bond specificity of neopullulanase. Barley alpha-amylase isozyme hybrids and Bacillus alpha-amylases demonstrate the impact of a small domain B protruding from the (beta/alpha)8-scaffold on the function and stability. Prospects for rational engineering in this family include important members of plant origin, such as alpha-amylase, starch branching and debranching enzymes, and amylomaltase.
Keyword	alpha-amylase [ Show all 14 ]

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