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alpha-glucosidase A, AglA, from Thermotoga maritima in complex with maltose and NAD+alpha-glucosidase A, AglA, from Thermotoga maritima in complex with maltose and NAD+
Structural highlights
FunctionAGLA_THEMA alpha-glycosidase with a very broad specificity hydrolyzes maltose and other small maltooligosaccharides but is inactive against the polymeric substrate starch agla is not specific with respect to the configuration at the c-4 position of its substrates because glycosidic derivatives of d-galactose are also hydrolyzed does not cleave beta-glycosidic bonds Evolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedGlycoside hydrolase family 4 represents an unusual group of glucosidases with a requirement for NAD+, divalent metal cations, and reducing conditions. The family is also unique in its inclusion of both alpha- and beta-specific enzymes. The alpha-glucosidase A, AglA, from Thermotoga maritima is a typical glycoside hydrolase family 4 enzyme, requiring NAD+ and Mn2+ as well as strongly reducing conditions for activity. Here we present the crystal structure of the protein complexed with NAD+ and maltose, refined at a resolution of 1.9 A. The NAD+ is bound to a typical Rossman fold NAD+-binding site, and the nicotinamide moiety is localized close to the maltose substrate. Within the active site the conserved Cys-174 and surrounding histidines are positioned to play a role in the hydrolysis reaction. The electron density maps indicate that Cys-174 is oxidized to a sulfinic acid. Most likely, the strongly reducing conditions are necessary to reduce the oxidized cysteine side chain. Notably, the canonical set of catalytic acidic residues common to other glucosidases is not present in the active site. This, combined with a high structural homology to NAD-dependent dehydrogenases, suggests an unusual and possibly unique mechanism of action for a glycoside-hydrolyzing enzyme. Crystal structure of Thermotoga maritima alpha-glucosidase AglA defines a new clan of NAD+-dependent glycosidases.,Lodge JA, Maier T, Liebl W, Hoffmann V, Strater N J Biol Chem. 2003 May 23;278(21):19151-8. Epub 2003 Feb 14. PMID:12588867[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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