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Phosphate Monoester Hydrolysis by Trinuclear Alkaline Phosphatase; DFT Study of Transition States and Reaction Mechanism

Authors

  • Prof. Shi-Lu Chen,

    Corresponding author
    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
    • Shi-Lu Chen, 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===

      Rong-Zhen Liao, Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)===

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  • Dr. Rong-Zhen Liao

    Corresponding author
    1. Department of Organic Chemistry, Arrhenius Laboratory, Stockholm University, 10691 Stockholm (Sweden)
    • Shi-Lu Chen, 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===

      Rong-Zhen Liao, 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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