Solvent oxygen is not incorporated into N 10‐formyltetrahydrofolate in the reaction catalyzed by N 10‐formyltetrahydrofolate synthetase

FEBS Letters

Jahansouz, Hossain¹  Himes, Richard H.¹  Song, Sophie¹ 

[1] Department of Biochemistry, University of Kansas, Lawrence, KS 66045-2106, USA

关键词: Formyltetrahydrofolate synthetase;    Formyltetrahydrofolate;    18O incorporation;   

DOI  :  10.1016/0014-5793(93)80502-L

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

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 H₂O would be incorporated into the formyl group of the N ₁₀-derivative. By conducting the reaction in a 1:1 mixture of [¹⁶O]H₂O and [¹⁸O]H₂O and using ¹³C NMR spectroscopy we show that no ¹⁸O is incorporated into the product and conclude that the reaction proceeds via a direct formylation of the N-10 position by formyl phosphate.

【 授权许可】

Unknown