title: Modified active site coordination in a clinical mutant of sulfite oxidase.
abstract: The molybdenum site of the Arginine 160 --> Glutamine clinical mutant of the physiologically vital enzyme sulfite oxidase has been investigated by a combination of X-ray absorption spectroscopy and density functional theory calculations. We conclude that the mutant enzyme has a six-coordinate pseudo-octahedral active site with coordination of Glutamine Oepsilon to molybdenum. This contrasts with the wild-type enzyme which is five-coordinate with approximately square-based pyramidal geometry. This difference in the structure of the molybdenum site explains many of the properties of the mutant enzyme which have previously been reported.
authors.affiliation: Department of Geological Sciences, University of Saskatchewan, Saskatoon, Saskatchewan, Canada.
authors.forename: Christian J
authors.initials: CJ
authors.lastname: Doonan
authors.forename: Heather L
authors.initials: HL
authors.lastname: Wilson
authors.forename: K V
authors.initials: KV
authors.lastname: Rajagopalan
authors.forename: Robert M
authors.initials: RM
authors.lastname: Garrett
authors.forename: Brian
authors.initials: B
authors.lastname: Bennett
authors.forename: Roger C
authors.initials: RC
authors.lastname: Prince
authors.forename: Graham N
authors.initials: GN
authors.lastname: George
mesh_terms: D000465:Algorithms; D001120:Arginine / Q000737:chemistry / Q000235:genetics; D001665:Binding Sites; D003198:Computer Simulation; D018360:Crystallography, X-Ray; D005973:Glutamine / Q000031:analogs & derivatives / Q000235:genetics; D006863:Hydrogen-Ion Concentration; D008982:Molybdenum / Q000737:chemistry*; D009154:Mutation; D009942:Organometallic Compounds / Q000737:chemistry*; D011487:Protein Conformation; D013057:Spectrum Analysis; D050876:Sulfite Oxidase / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D014965:X-Rays
chemical_list: D009942:Organometallic Compounds; D005973:Glutamine; D008982:Molybdenum; D001120:Arginine; D050876:Sulfite Oxidase