Direct 19F NMR observation of the conformational selection of optically active rotamers of the antifolate compound fluoronitropyrimethamine bound to the enzyme dihydrofolate reductase

FEBS Letters

Stevens, Malcolm F.G.¹  Birdsall, Berry²  Griffin, Roger J.¹  Tendler, Saul J.B.²  Feeney, James²  Roberts, Gordon C.K.³ 

[1] Pharmaceutical Sciences Institute, Department of Pharmaceutical Sciences, Aston University, Birmingham B4 7ET, England;Division of Physical Biochemistry, National Institute for Medical Research, Mill Hill, London NW7 1AA, England;Department of Biochemistry, Leicester University, Leicester LE1 7RH, England

关键词: Dihydrofolate reductase;    19F-NMR;    Pyrimethamine;    Antifolate;    Conformational selection;   

DOI  :  10.1016/0014-5793(88)80368-5

学科分类：生物化学/生物物理

来源: John Wiley & Sons Ltd.

【 摘 要 】

The molecular basis of the binding of the lipophilic antifolate compound fluoronitropyrimethamine [2,4-diamino-5-(4-fluoro-3-nitrophenyl)-6-ethylpyrimidine] to its target enzyme dihydrofolate reductase has been investigated using a combination of ¹⁹F NMR spectroscopy and molecular mechanical calculations. ¹⁹F NMR reveals the presence of two different conformational states for the fluoronitropyrimethamine-Lactobacillus casei enzyme complex. MM2 molecular mechanical calculations predict restricted rotation about the C5-C1′ bond of the ligand and this gives rise to two slowly interconverting rotamers which are an enantiomeric pair. The results of ¹⁹F NMR spectroscopy reveal that both these isomers bind to the enzyme, with different affinities. There is no detectable interconversion of the bound rotamers themselves on the NMR timescale. The effect of the addition of co-enzyme to the sample is to reverse the preference the enzyme has for each rotamer.

【 授权许可】

Unknown