title: Mutations affecting the internal equilibrium of the reaction catalyzed by 6-aminohexanoate-dimer hydrolase.
abstract: The enzyme 6-aminohexanoate-dimer hydrolase catalyzes amide synthesis. The yield of this reverse reaction in 90% t-butyl alcohol was found to vary drastically when enzyme mutants with substitutions of several amino acids located at the entrance of the catalytic cleft were used. Movement of the loop region and the flip-flop of Tyr170 generate a local hydrophobic environment at the catalytic center of the enzyme. Here, we propose that the shift of the internal equilibrium between the enzyme-substrate complex and enzyme-product complex by the 'water-excluding effect' alters the rate of the forward and reverse reactions. Moreover, we suggest that the local hydrophobic environment potentially provides a reaction center suitable for efficient amide synthesis.
  
  
  
  PDB code 3VWL: Hyb-24DNY-S(187) PDB code 3VWM: Hyb-24DNY-A(187) PDB code 3VWN: Hyb-24DNY-G(187) PDB code 3A65: Hyb-24DN-A(112) /Ahx complex PDB code 3A66: Hyb-24DNY-A(112) /Ahx complex PDB code 3VWP: Hyb-24DNY-S(187) A(112) /Ahx complex PDB code 3VWQ: Hyb-24DNY-A(187) A(112) /Ahx complex PDB code 3VWR: Hyb-24DNY-G(187) A(112) /Ahx complex.
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan. negoro@eng.u-hyogo.ac.jp.
authors.forename: Seiji
authors.initials: S
authors.lastname: Negoro
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Yasuyuki
authors.initials: Y
authors.lastname: Kawashima
authors.affiliation: Department of Life Science, Graduate School of Life Science, University of Hyogo, Himeji, Hyogo, Japan. shibach@sci.u-hyogo.ac.jp.
authors.forename: Naoki
authors.initials: N
authors.lastname: Shibata
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Tatsuya
authors.initials: T
authors.lastname: Kobayashi
authors.affiliation: Department of Material Engineering Science, Graduate School of Engineering Science, Osaka University, Suita, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Baba
authors.affiliation: Institute for Protein Research, Osaka University, Suita, Japan.
authors.forename: Young-Ho
authors.initials: YH
authors.lastname: Lee
authors.affiliation: Center for Basic Education and Integrated Learning, Kanagawa Institute of Technology, Atsugi, Kanagawa, Japan.
authors.forename: Katsumasa
authors.initials: K
authors.lastname: Kamiya
authors.affiliation: Center for Computational Sciences, University of Tsukuba, Ibaraki, Japan. shigeta@ccs.tsukuba.ac.jp.
authors.forename: Yasuteru
authors.initials: Y
authors.lastname: Shigeta
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Keisuke
authors.initials: K
authors.lastname: Nagai
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Ikki
authors.initials: I
authors.lastname: Takehara
authors.affiliation: Graduate School of Science and Engineering, Kagoshima University, Japan.
authors.forename: Dai-Ichiro
authors.initials: D
authors.lastname: Kato
authors.affiliation: Department of Applied Chemistry, Graduate School of Engineering, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Masahiro
authors.initials: M
authors.lastname: Takeo
authors.affiliation: Department of Life Science, Graduate School of Life Science, University of Hyogo, Himeji, Hyogo, Japan.
authors.forename: Yoshiki
authors.initials: Y
authors.lastname: Higuchi
mesh_terms: D000581:Amidohydrolases / Q000737:chemistry* / Q000235:genetics / Q000378:metabolism; D020134:Catalytic Domain; D062105:Molecular Docking Simulation; D020125:Mutation, Missense
chemical_list: D000581:Amidohydrolases; C026250:6-aminohexanoate-dimer hydrolase
keywords: 6-aminohexanoate-dimer hydrolase; amide synthesis; induced-fit mechanism; internal equilibrium; x-ray crystallography