Enantioselectivity of haloalkane dehalogenase LinB on the degradation of 1,2-dichloropropane: A QM/MM study |
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| Affiliation: | 1. Anastro Laboratory, Department of Chemistry, Changwon National University, Changwon 641-773, Republic of Korea;2. Environment Research Institute, Shandong University, Jinan 250100, China;3. Yanbian University Hospital, Yanji, Jinlin, 133000, China;1. Shandong Key Laboratory of Water Pollution Control and Resource Reuse, School of Environmental Science and Engineering, Shandong University, Jinan 250100, PR China;2. Environment Research Institute, Shandong University, Jinan 250100, PR China;3. School of Chemistry and Chemical Engineering, Shandong University, Jinan 250100, PR China;1. Departamento de Ingenierías del Centro Universitario de Tonalá, Universidad de Guadalajara, Av. Nuevo Periférico 555, Ejido San José Tatepozco, C.P. 45425 Tonalá, Jalisco, Mexico;2. Unidad de Servicios de Apoyo en Resolución Analítica, Universidad Veracruzana, Apdo. Postal 575, Xalapa, Ver., Mexico |
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| Abstract: | The hydrolysis dechlorination mechanism of a chiral organochlorine pollutant, 1,2-dichloropropane (DCP), catalyzed by haloalkane dehalogenase LinB has been investigated by using a combined quantum mechanics/molecular mechanics method. LinB was confirmed to be enantioselective towards the catabolism of the racemic mixture. Based on the SN2 nucleophilic substitution mechanism, the dechlorination process was identified as the rate-determining step in LinB-catalyzed degradation of 1,2-dichloropropane, the Boltzmann-weighted average potential barrier of which is 18.8 kcal/mol for the (R)-isomer and 24.0 kcal/mol for the (S)-isomer. A particular water molecule near (S)-DCP in the reaction system can strongly disturb the dechlorination process, which can account for the enantioselectivity of LinB. Further electrostatic influence analysis indicates that proper mutation of Gly37 may improve the catalytic efficiency of LinB towards DCP. |
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| Keywords: | Haloalkane dehalogenase 1,2-Dichloropropane Enantioselectivity Quantum mechanics/molecular mechanics Boltzmann-weighted average |
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