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Crystal structure of maltohexaose-producing amylase from alkalophilic Bacillus sp.707.Crystal structure of maltohexaose-producing amylase from alkalophilic Bacillus sp.707.
Structural highlights
FunctionEvolutionary Conservation Check, as determined by ConSurfDB. You may read the explanation of the method and the full data available from ConSurf. Publication Abstract from PubMedMaltohexaose-producing amylase, called G6-amylase (EC 3.2.1.98), from alkalophilic Bacillus sp.707 predominantly produces maltohexaose (G6) from starch and related alpha-1,4-glucans. To elucidate the reaction mechanism of G6-amylase, the enzyme activities were evaluated and crystal structures were determined for the native enzyme and its complex with pseudo-maltononaose at 2.1 and 1.9 A resolutions, respectively. The optimal condition for starch-degrading reaction activity was found at 45 degrees C and pH 8.8, and the enzyme produced G6 in a yield of more than 30% of the total products from short-chain amylose (DP = 17). The crystal structures revealed that Asp236 is a nucleophilic catalyst and Glu266 is a proton donor/acceptor. Pseudo-maltononaose occupies subsites -6 to +3 and induces the conformational change of Glu266 and Asp333 to form a salt linkage with the N-glycosidic amino group and a hydrogen bond with secondary hydroxyl groups of the cyclitol residue bound to subsite -1, respectively. The indole moiety of Trp140 is stacked on the cyclitol and 4-amino-6-deoxyglucose residues located at subsites -6 and -5 within a 4 A distance. Such a face-to-face short contact may regulate the disposition of the glucosyl residue at subsite -6 and would govern the product specificity for G6 production. Biochemical and crystallographic analyses of maltohexaose-producing amylase from alkalophilic Bacillus sp. 707.,Kanai R, Haga K, Akiba T, Yamane K, Harata K Biochemistry. 2004 Nov 9;43(44):14047-56. PMID:15518553[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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