A1 Refereed original research article in a scientific journal
Hydrolytic dethiophosphorylation and desulfurization of the monothioate analogues of uridine monophosphates under acidic conditions
Authors: Ora M, Oivanen M, Lonnberg H
Publisher: ROYAL SOC CHEMISTRY
Publication year: 1996
Journal:: Royal Society of Chemistry. Journal: Perkin Transactions 2
Journal name in source: JOURNAL OF THE CHEMICAL SOCIETY-PERKIN TRANSACTIONS 2
Journal acronym: J CHEM SOC PERK T 2
Issue: 5
First page : 771
Last page: 774
Number of pages: 4
ISSN: 0300-9580
DOI: https://doi.org/10.1039/p29960000771
Abstract
The hydrolytic reactions of uridine 2'-, 3'- and 5'-phosphoromonothioates (2'-, 3'- and 5'-UMPS) under acidic and neutral conditions have been followed by HPLC. Under slightly acidic conditions (pH 2-5), only pa-independent dethiophosphorylation to uridine takes place. This reaction is 200- to 300-fold as fast as dephosphorylation of the corresponding uridine monophosphates (UMP), presumably due to higher stability of the thiometaphosphate monoanion compared to metaphosphate anion. At pH > 5, i.e. at pH > pK(a2) of the thiophosphate moiety, the dethiophosphorylation is retarded with increasing basicity of the solution. At pH < 1, acid-catalysed desulfurization of 2'- and 3'-UMPS to an isomeric mixture of 2'/3'-UMP competes with their dethiophosphorylation. This reaction is suggested to proceed by a nucleophilic attack of the neighbouring hydroxy group on phosphorus. No such reaction occurs with 5'-UMPS. In contrast to 2'- and 3'-UMP, no sign of interconversion of 2'- and 3'-UMPS is detected.
The hydrolytic reactions of uridine 2'-, 3'- and 5'-phosphoromonothioates (2'-, 3'- and 5'-UMPS) under acidic and neutral conditions have been followed by HPLC. Under slightly acidic conditions (pH 2-5), only pa-independent dethiophosphorylation to uridine takes place. This reaction is 200- to 300-fold as fast as dephosphorylation of the corresponding uridine monophosphates (UMP), presumably due to higher stability of the thiometaphosphate monoanion compared to metaphosphate anion. At pH > 5, i.e. at pH > pK(a2) of the thiophosphate moiety, the dethiophosphorylation is retarded with increasing basicity of the solution. At pH < 1, acid-catalysed desulfurization of 2'- and 3'-UMPS to an isomeric mixture of 2'/3'-UMP competes with their dethiophosphorylation. This reaction is suggested to proceed by a nucleophilic attack of the neighbouring hydroxy group on phosphorus. No such reaction occurs with 5'-UMPS. In contrast to 2'- and 3'-UMP, no sign of interconversion of 2'- and 3'-UMPS is detected.
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