Sunday, July 29, 2007
P15

Arginine 129 of Rhodochrous rhodococcus Nitrilase Plays a Crucial Role in Aromatic Substrate Binding

Soo-Jin Yeom1, Hye-Jung Kim1, Jung-Kul Lee2, and Deok-Kun Oh1. (1) Department of Bioscience and biotechnology, Konkuk University, Seoul, South Korea, (2) Department of chemical engineering, Konkuk University, Seoul, South Korea

Molecular modeling and mutational analysis were used to probe the molecular determinants of substrate specificity for aliphatic and aromatic nitriles of nitrilase from Rhodococcus rhodochrous. Among seven putative substrate-contacting residues, Ala-substitution at Arg-129 resulted in the complete loss of nitrilase activity, suggesting that the residue play an important role in its catalytic mechanism. When Arg-129 was further mutated to Val, Tyr, Asp, Glu, Lys, and Trp, respectively, only wild-type nitrilase and mutant R129K exhibited catalytic activity for aromatic nitriles such as benzonitrile, 2-cyanopyridine, m-tolunitrile. These results demonstrate that the positively charged amino acid at position 129 plays a crucial role in aromatic substrate binding.


Web Page: www.konkuk.ac.kr/~deokkun

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