Phosphate Monoester Hydrolysis by Trinuclear Alkaline Phosphatase; DFT Study of Transition States and Reaction Mechanism |
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Authors: | Prof. Shi‐Lu Chen Dr. Rong‐Zhen Liao |
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Affiliation: | 1. Key Laboratory of Cluster Science of Ministry of Education, Beijing Key Laboratory of Photoelectronic/Electrophotonic, Conversion Materials, School of Chemistry, Beijing Institute of Technology, Beijing 100081 (China), Fax: (+86)?01‐6891‐1354;2. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden) |
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Abstract: | Alkaline phosphatase (AP) is a trinuclear metalloenzyme that catalyzes the hydrolysis of a broad range of phosphate monoesters to form inorganic phosphate and alcohol (or phenol). In this paper, by using density functional theory with a model based on a crystal structure, the AP‐catalyzed hydrolysis of phosphate monoesters is investigated by calculating two substrates, that is, methyl and p‐nitrophenyl phosphates, which represent alkyl and aryl phosphates, respectively. The calculations confirm that the AP reaction employs a “ping‐pong” mechanism involving two chemical displacement steps, that is, the displacement of the substrate leaving group by a Ser102 alkoxide and the hydrolysis of the phosphoseryl intermediate by a Zn2‐bound hydroxide. Both displacement steps proceed via a concerted associative pathway no matter which substrate is used. Other mechanistic aspects are also studied. Comparison of our calculations with linear free energy relationships experiments shows good agreement. |
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Keywords: | alkaline phosphatase associative mechanism density functional calculations enzyme catalysis phosphate ester hydrolysis |
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