title: Structure determination of selenomethionyl S-adenosylhomocysteine hydrolase using data at a single wavelength.
abstract: S-Adenosylhomocysteine (AdoHcy) hydrolase regulates all adenosylmethionine-(AdoMet) dependent transmethylations by hydrolyzing the potent feedback inhibitor AdoHcy to homocysteine and adenosine. The crystallographic structure determination of a selenomethionyl-incorporated AdoHcy hydrolase inhibitor complex was accomplished using single wavelength anomalous diffraction data and the direct methods program, Snb v2.0, which produced the positions of all 30 crystallographically distinct selenium atoms. The mode of enzyme-cofactor binding is unique, requiring interactions from two protein monomers. An unusual dual role for a catalytic water molecule in the active site is revealed in the complex with the adenosine analog 2'-hydroxy, 3'-ketocyclopent-4'-enyladenine.
authors.affiliation: Structural Biology and Biochemistry, Research Institute, Hospital for Sick Children, Toronto, Ontario, Canada.
authors.forename: M A
authors.initials: MA
authors.lastname: Turner
authors.forename: C S
authors.initials: CS
authors.lastname: Yuan
authors.forename: R T
authors.initials: RT
authors.lastname: Borchardt
authors.forename: M S
authors.initials: MS
authors.lastname: Hershfield
authors.forename: G D
authors.initials: GD
authors.lastname: Smith
authors.forename: P L
authors.initials: PL
authors.lastname: Howell
mesh_terms: D043383:Adenosylhomocysteinase; D001665:Binding Sites; D002384:Catalysis; D018360:Crystallography, X-Ray; D006801:Humans; D006867:Hydrolases / Q000737:chemistry*; D046911:Macromolecular Substances; D008958:Models, Molecular; D009243:NAD / Q000378:metabolism; D012435:S-Adenosylhomocysteine / Q000737:chemistry*; D012436:S-Adenosylmethionine / Q000737:chemistry*; D012996:Solutions
chemical_list: D046911:Macromolecular Substances; D012996:Solutions; D009243:NAD; D012436:S-Adenosylmethionine; D012435:S-Adenosylhomocysteine; D006867:Hydrolases; D043383:Adenosylhomocysteinase