title: Phosphate monoester hydrolysis by trinuclear alkaline phosphatase; DFT study of transition States and reaction mechanism.
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.
authors.affiliation: 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. shlchen@bit.edu.cn.
authors.forename: Shi-Lu
authors.initials: SL
authors.lastname: Chen
authors.forename: Rong-Zhen
authors.initials: RZ
authors.lastname: Liao
mesh_terms: D000469:Alkaline Phosphatase / Q000737:chemistry*; D002384:Catalysis; D006868:Hydrolysis; D008667:Metalloproteins / Q000737:chemistry; D009596:Nitrophenols / Q000737:chemistry; D009943:Organophosphorus Compounds / Q000737:chemistry; D010710:Phosphates / Q000737:chemistry*; D013379:Substrate Specificity
chemical_list: D008667:Metalloproteins; D009596:Nitrophenols; D009943:Organophosphorus Compounds; D010710:Phosphates; C008644:nitrophenylphosphate; D000469:Alkaline Phosphatase
keywords: alkaline phosphatase; associative mechanism; density functional calculations; enzyme catalysis; phosphate ester hydrolysis