1d3c
MICHAELIS COMPLEX OF BACILLUS CIRCULANS STRAIN 251 CYCLODEXTRIN GLYCOSYLTRANSFERASE WITH GAMMA-CYCLODEXTRINMICHAELIS COMPLEX OF BACILLUS CIRCULANS STRAIN 251 CYCLODEXTRIN GLYCOSYLTRANSFERASE WITH GAMMA-CYCLODEXTRIN
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 PubMedThe enzyme cyclodextrin glycosyltransferase is closely related to alpha-amylases but has the unique ability to produce cyclodextrins (circular alpha(1-->4)-linked glucoses) from starch. To characterize this specificity we determined a 1.8-A structure of an E257Q/D229N mutant cyclodextrin glycosyltransferase in complex with its product gamma-cyclodextrin, which reveals for the first time how cyclodextrin is competently bound. Across subsites -2, -1, and +1, the cyclodextrin ring binds in a twisted mode similar to linear sugars, giving rise to deformation of its circular symmetry. At subsites -3 and +2, the cyclodextrin binds in a manner different from linear sugars. Sequence comparisons and site-directed mutagenesis experiments support the conclusion that subsites -3 and +2 confer the cyclization activity in addition to subsite -6 and Tyr-195. On this basis, a role of the individual residues during the cyclization reaction cycle is proposed. The cyclization mechanism of cyclodextrin glycosyltransferase (CGTase) as revealed by a gamma-cyclodextrin-CGTase complex at 1.8-A resolution.,Uitdehaag JC, Kalk KH, van Der Veen BA, Dijkhuizen L, Dijkstra BW J Biol Chem. 1999 Dec 3;274(49):34868-76. PMID:10574960[1] From MEDLINE®/PubMed®, a database of the U.S. National Library of Medicine. See AlsoReferences |
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