title: Crystal structure of nitrile hydratase from a thermophilic Bacillus smithii.
abstract: The crystal structure of the nitrile hydratase (NHase) from Bacillus smithii SC-J05-1 was determined. Our analysis of the structure shows that some residues that seem to be responsible for substrate recognition are different from those of other NHases. In particular, the Phe52 in the beta subunit of NHase from B. smithii covers the metal center partially like a small lid and narrows the active site cleft. It is well known that the NHase from B. smithii especially prefers aliphatic nitriles for its substrate rather than aromatic ones, and we can now infer that the Phe52 residue may play a key role in the substrate specificity for this enzyme. This finding leads us to suggest that substitution of these residues may alter the substrate specificity of the enzyme.
authors.affiliation: Sumitomo Chemical Co, Ltd. Environmental Health Science Laboratory, 3-1-98 Kasugade-naka, Konohanaku, Osaka 554-8558, Japan. hourai@sc.sumitomo-chem.co.jp
authors.forename: Shinji
authors.initials: S
authors.lastname: Hourai
authors.forename: Misao
authors.initials: M
authors.lastname: Miki
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Takashima
authors.forename: Satoshi
authors.initials: S
authors.lastname: Mitsuda
authors.forename: Kazunori
authors.initials: K
authors.lastname: Yanagi
mesh_terms: D001407:Bacillus / Q000737:chemistry* / Q000145:classification / Q000201:enzymology*; D001665:Binding Sites; D003198:Computer Simulation; D003461:Crystallography / Q000379:methods*; D019281:Dimerization; D004789:Enzyme Activation; D006836:Hydro-Lyases / Q000737:chemistry* / Q000378:metabolism*; D046911:Macromolecular Substances; D008958:Models, Molecular; D011485:Protein Binding; D011487:Protein Conformation; D021122:Protein Subunits; D013045:Species Specificity; D013329:Structure-Activity Relationship
chemical_list: D046911:Macromolecular Substances; D021122:Protein Subunits; D006836:Hydro-Lyases; C048831:nitrile hydratase