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The Determination of Protease Specificity in Mouse Tissue Extracts by MALDI-TOF Mass Spectrometry: Manipulating PH to Cause Specificity Changes
Published on: May 25, 2018
Optimum substrate size and specific anomer requirements for the reducing-end glycoside hydrolase
Nathan N Aronson1, Brian A Halloran
1Department of Biochemistry and Molecular Biology, University of South Alabama, Mobile, AL 36688, USA. naronson@jaguar1.usouthal.edu
Abstract:
Di-N-acetylchitobiase is a family 18 glycoside hydrolase that splits the reducing-end GlcNAc from chitooligosaccharides. The enzyme hydrolyzed only the alpha-anomer of five tested substrates, chitin di- through hexasaccharide. In all cases the glycosyl fragment retained its beta-configuration while the split monosaccharide was alpha-D-GlcNAc. Chitobiose was hydrolyzed less than half as fast as the other larger substrates. All four of them, tri- to hexasaccharide, reacted at the same rate. The biochemical behavior of di-N-acetylchitobiase indicates it has three subsites, -2, -1, +1, in which the reducing-end trimer of any sized chitooligosaccharide is bound. The +1 site is specific for an alpha-anomer.