title: X-ray structures along the reaction pathway of cyclodextrin glycosyltransferase elucidate catalysis in the alpha-amylase family.
abstract: Cyclodextrin glycosyltransferase (CGTase) is an enzyme of the alpha-amylase family, which uses a double displacement mechanism to process alpha-linked glucose polymers. We have determined two X-ray structures of CGTase complexes, one with an intact substrate at 2.1 A resolution, and the other with a covalently bound reaction intermediate at 1.8 A resolution. These structures give evidence for substrate distortion and the covalent character of the intermediate and for the first time show, in atomic detail, how catalysis in the alpha-amylase family proceeds by the concerted action of all active site residues.
authors.affiliation: BIOSON Research Institute, University of Groningen, The Netherlands.
authors.forename: J C
authors.initials: JC
authors.lastname: Uitdehaag
authors.forename: R
authors.initials: R
authors.lastname: Mosi
authors.forename: K H
authors.initials: KH
authors.lastname: Kalk
authors.forename: B A
authors.initials: BA
authors.lastname: van der Veen
authors.forename: L
authors.initials: L
authors.lastname: Dijkhuizen
authors.forename: S G
authors.initials: SG
authors.lastname: Withers
authors.forename: B W
authors.initials: BW
authors.lastname: Dijkstra
mesh_terms: D001407:Bacillus / Q000201:enzymology; D001665:Binding Sites; D002384:Catalysis; D003460:Crystallization; D018360:Crystallography, X-Ray; D004583:Electrons; D005964:Glucosyltransferases / Q000737:chemistry* / Q000378:metabolism*; D006860:Hydrogen Bonding; D008956:Models, Chemical; D008958:Models, Molecular; D008969:Molecular Sequence Data; D009844:Oligosaccharides / Q000737:chemistry / Q000378:metabolism; D011485:Protein Binding; D011487:Protein Conformation; D013329:Structure-Activity Relationship; D014312:Trisaccharides / Q000737:chemistry / Q000378:metabolism; D000516:alpha-Amylases / Q000737:chemistry / Q000378:metabolism*
chemical_list: D009844:Oligosaccharides; D014312:Trisaccharides; C008317:maltotriose; C101184:maltononaose; D005964:Glucosyltransferases; C019963:cyclomaltodextrin glucanotransferase; D000516:alpha-Amylases