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Crystal Structure of Thermoactinomyces vulgaris R-47 Alpha-Amylase 1 (TVAI) Mutant D356N complexed with P2, a pullulan model oligosaccharideCrystal Structure of Thermoactinomyces vulgaris R-47 Alpha-Amylase 1 (TVAI) Mutant D356N complexed with P2, a pullulan model oligosaccharide
Structural highlights
FunctionNEPU1_THEVU Endohydrolysis of 1,4-alpha-glucosidic linkages in pullulan to form panose. Also hydrolyzes cyclodextrins. 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 PubMedThermoactinomyces vulgaris R-47 alpha-amylase 1 (TVAI) has unique hydrolyzing activities for pullulan with sequence repeats of alpha-(1,4), alpha-(1,4), and alpha-(1,6) glycosidic linkages, as well as for starch. TVAI mainly hydrolyzes alpha-(1,4) glycosidic linkages to produce a panose, but it also hydrolyzes alpha-(1,6) glycosidic linkages with a lesser efficiency. X-ray structures of three complexes comprising an inactive mutant TVAI (D356N or D356N/E396Q) and a pullulan model oligosaccharide (P2; [Glc-alpha-(1,6)-Glc-alpha-(1,4)-Glc-alpha-(1,4)]2 or P5; [Glc-alpha-(1,6)-Glc-alpha-(1,4)-Glc-alpha-(1,4)]5) were determined. The complex D356N/P2 is a mimic of the enzyme/product complex in the main catalytic reaction of TVAI, and a structural comparison with Aspergillus oryzaealpha-amylase showed that the (-) subsites of TVAI are responsible for recognizing both starch and pullulan. D356N/E396Q/P2 and D356N/E396Q/P5 provided models of the enzyme/substrate complex recognizing the alpha-(1,6) glycosidic linkage at the hydrolyzing site. They showed that only subsites -1 and -2 at the nonreducing end of TVAI are effective in the hydrolysis of alpha-(1,6) glycosidic linkages, leading to weak interactions between substrates and the enzyme. Domain N of TVAI is a starch-binding domain acting as an anchor in the catalytic reaction of the enzyme. In this study, additional substrates were also found to bind to domain N, suggesting that domain N also functions as a pullulan-binding domain. Complexes of Thermoactinomyces vulgaris R-47 alpha-amylase 1 and pullulan model oligossacharides provide new insight into the mechanism for recognizing substrates with alpha-(1,6) glycosidic linkages.,Abe A, Yoshida H, Tonozuka T, Sakano Y, Kamitori S FEBS J. 2005 Dec;272(23):6145-53. PMID:16302977[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences
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