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Solvent oxygen is not incorporated into N 10 ‐formyltetrahydrofolate in the reaction catalyzed by N 10 ‐formyltetrahydrofolate synthetase
Author(s) -
Song Sophie,
Jahansouz Hossain,
Himes Richard H.
Publication year - 1993
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(93)80502-l
Subject(s) - formylation , chemistry , catalysis , nucleophile , solvent , derivative (finance) , oxygen , medicinal chemistry , reaction intermediate , reaction mechanism , phosphate , pyrazine , stereochemistry , organic chemistry , financial economics , economics
The mechanism of the reaction catalyzed by N 10 ‐formyltetrahydrofolate synthetase involves the formation of formyl phosphate as an intermediate which then formylates tetrahydrofolate at the N‐10 position. Previous studies demonstrated that the non‐enzymic formylation of tetrahydrofolate by formyl phosphate occurs exclusively at the more nucleophilic 5‐nitrogen in the reduced pyrazine ring. The experiments described in this report were designed to determine whether N 5 ‐formyltetrahydrofolate might be the first product to be formed on the enzyme, followed by formyl transfer to the 10‐nitrogen via the cyclic intermediate n 5,10 ‐methenyltetrahydrofolate. If this were the case, oxygen from solvent H 2 O would be incorporated into the formyl group of the N 10 ‐derivative. By conducting the reaction in a 1:1 mixture of [ 16 O]H 2 O and [ 18 O]H 2 O and using 13 C NMR spectroscopy we show that no 18 O is incorporated into the product and conclude that the reaction proceeds via a direct formylation of the N‐10 position by formyl phosphate.