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United States Department of Agriculture

Agricultural Research Service

Title: Cyclic Products from Alternan

Authors
item Cote, Gregory
item Ahlgren, Jeffrey
item Biely, Peter - SLOVAK ACAD OF SCIENCES

Submitted to: American Chemical Society Abstracts
Publication Type: Abstract Only
Publication Acceptance Date: May 1, 2000
Publication Date: N/A

Technical Abstract: Alternanase is an enzyme which endo-hydrolytically cleaves the alpha- (1-3), alpha-(1-6)-linked D-glucan alternan. Enzymatic hydrolysis of alternan produces a series of oligosaccharides, the main product being a cyclic tetrasaccharide of D-glucose with alternating alpha-(1-3) and alpha-(1-6) linkages. An improved method for larger-scale preparation of the enzyme will be described. We also have developed an aqueous-based system for the preparation of gram-quantities of the cyclic tetrasaccharide. This protocol involves removal of reducing saccharides by ion-exchange at high pH, followed by gel-filtration chromatography. These improved methods have allowed us to prepare sufficient material for further studies, including inhibition studies. We found that alternanase is inhibited by its own products. Isomaltose exhibited a Ki of 15 mM, and the cyclic tetrasaccharide exhibited a Ki of 4 mM. Furthermore, the enzyme is also capable of hydrolyzing the cyclic tetramer at relatively slow rates. Studies on the action of alternanase on several oligosaccharide analogues of alternan will also be described.

Last Modified: 4/18/2014
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