1d3c
From Proteopedia
MICHAELIS COMPLEX OF BACILLUS CIRCULANS STRAIN 251 CYCLODEXTRIN GLYCOSYLTRANSFERASE WITH GAMMA-CYCLODEXTRIN
Overview
The 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.
About this Structure
1D3C is a Single protein structure of sequence from Bacillus circulans. Full crystallographic information is available from OCA.
Reference
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 Page seeded by OCA on Fri May 2 13:24:13 2008
Categories: Bacillus circulans | Cyclomaltodextrin glucanotransferase | Single protein | Dijkhuizen, L. | Dijkstra, B W. | Kalk, K H. | Uitdehaag, J C.M. | Veen, B A.van der. | Alpha-amylase | Catalysis | Family 13 glycosyl hydrolase | Induced fit | Oligosaccharide | Product complex | Transglycosylation
