title: Roles of Ile66 and Ala107 of D-psicose 3-epimerase from Agrobacterium tumefaciens in binding O6 of its substrate, D-fructose.
abstract: Using site-directed mutagenesis, we investigated the roles of Ile66 and Ala107 of D: -psicose 3-epimerase from Agrobacterium tumefaciens in binding O6 of its true substrate, D: -fructose. When Ile66 was substituted with alanine, glycine, cysteine, leucine, phenylalanine, tryptophan, tyrosine or valine, all the mutants dramatically increased the K (m) for D: -tagatose but slightly decreased the K (m) for D: -fructose, indicating that Ile66 is involved in substrate recognition. When Ala107 was substituted by either isoleucine or valine, the substituted mutants had lower thermostability than the wild-type enzyme whereas the proline-substituted mutant had higher thermostability. Thus, Ala107 is involved in enzyme stability.
authors.affiliation: Department of Bioscience and Biotechnology, Konkuk University, 1 Hwayang-dong, Gwangjin-gu, Seoul, 143-701, South Korea.
authors.forename: Hye-Jung
authors.initials: HJ
authors.lastname: Kim
authors.forename: Byung-Chul
authors.initials: BC
authors.lastname: Lim
authors.forename: Soo-Jin
authors.initials: SJ
authors.lastname: Yeom
authors.forename: Yeong-Su
authors.initials: YS
authors.lastname: Kim
authors.forename: Dooil
authors.initials: D
authors.lastname: Kim
authors.forename: Deok-Kun
authors.initials: DK
authors.lastname: Oh
mesh_terms: D016960:Agrobacterium tumefaciens / Q000201:enzymology*; D001426:Bacterial Proteins / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D004795:Enzyme Stability; D005632:Fructose / Q000378:metabolism*; D007700:Kinetics; D056004:Molecular Dynamics Simulation; D016297:Mutagenesis, Site-Directed; D017433:Protein Structure, Secondary; D019998:Racemases and Epimerases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism*; D013329:Structure-Activity Relationship; D013379:Substrate Specificity
chemical_list: D001426:Bacterial Proteins; C003243:psicose; D005632:Fructose; D019998:Racemases and Epimerases