Title

Generality of Solvation Effects on the Hydrolysis Rates of Phosphate Monoesters, and TheirPossible Relevance to Enzymatic Catalysis

Document Type

Article

Journal/Book Title

Journal of Organic Chemistry

Publication Date

2002

Volume

67

Issue

4

First Page

1214

Last Page

1220

Abstract

Previous work by Kirby and co-workers revealed a significant acceleration of the rate of hydrolysis of p-nitrophenyl phosphate by added dipolar solvents such as DMSO. Activation parameters and kinetic isotope effects have been measured to ascertain the origin of this effect. The generality of this phenomenon was examined with a series of esters with more basic leaving groups. Computational analyses of the effects of desolvation of dianionic phosphate monoesters were carried out, and the possible effect of the transfer from water to the active site of alkaline phosphatase was modeled. The results are consistent with a desolvation-induced weakening of the P−O ester bond in the ground state. Other aryl phosphate esters show similar rate accelerations at high fractions of DMSO, but phenyl and methyl phosphates do not, and their hydrolysis reactions are actually slowed by these conditions.

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