Mutations affecting the internal equilibrium of the reaction catalyzed by 6-aminohexanoate-dimer hydrolase

作者：Negoro Seiji^*; Kawashima Yasuyuki; Shibata Naoki^*; Kobayashi Tatsuya; Baba Takeshi; Lee Young Ho; Kamiya Katsumasa; Shigeta Yasuteru^*; Nagai Keisuke; Takehara Ikki; Kato Dai ichiro; Takeo Masahiro; Higuchi Yoshiki

来源：FEBS LETTERS, 2016, 590(18): 3133-3143.

DOI：10.1002/1873-3468.12354

• 6-aminohexanoate-dimer hydrolase
• amide synthesis
• induced-fit mechanism
• internal equilibrium
• x-ray crystallography

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.
DatabasePDB code : Hyb-24DNY-S-187 PDB code : Hyb-24DNY-A(187) PDB code : Hyb-24DNY-G(187) PDB code : Hyb-24DN-A(112)/Ahx complex PDB code : Hyb-24DNY-A(112)/Ahx complex PDB code : Hyb-24DNY-S(187)A(112)/Ahx complex PDB code : Hyb-24DNY-A(187)A(112)/Ahx complex PDB code : Hyb-24DNY-G(187)A(112)/Ahx complex

• 出版日期2016-9