Semiempirical molecular orbital studies: the mechanism of the lipase-catalyzed ester hydrolysis in acylation step

Advancing the chemical engineering fundamentals

Catalysis (T2-13P)

Prof Hsuan-Liang Liu
National Taipei University of Technology
Department of Chemical Engineering and Biotechnology
1 Sec. 3 ZhongXiao E. Rd., Taipei, Taiwan
Taiwan, Province of China

Mr Jian-Hua Zhao
National Taipei University of Technology
Department of Chemical Engineering and Biotechnology
1 Sec. 3 ZhongXiao E. Rd., Taipei, Taiwan
Taiwan, Province of China

Keywords: serine hydrolase; catalytic triad; oxyanion hole

We present the results from semiempirical molecular orbital calculations for the acylation step in the lipase-catalyzed ester hydrolysis. The results of our model reveal that the lowest energy path for the formation of the tetrahedral intermediate is for the serine residue to approach the substrate, followed by coupling heavy atom movement and proton transfer. Our calculations also show that the cooperation of the aspartate group and the oxyanion hole is capable of lowering the activation barrier by about 16 kcal/mol. Our results further suggest that the lipase-catalyzed ester hydrolysis adopts the single proton transfer mechanism.

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Presented Wednesday 19, 13:30 to 15:00, in session Catalysis (T2-13P).