19F NMR Studies on 8-Fluoroflavins and 8-Fluoro Flavoproteins

Peter Macheroux, Christopher L. Kojiro, Lawrence M. Schopfer, Sumita Chakraborty, Vincent Massey

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Abstract

The 19F NMR spectra of the oxidized and reduced forms of 8-fluororiboflavin, 8-fluoro-FAD, and the 8-fluoroflavin-reconstituted flavoproteins flavodoxin, riboflavin binding protein, D-amino acid oxidase, p-hydroxybenzoate hydroxylase, Old Yellow Enzyme, anthranilate hydroxylase, general acyl-CoA dehydrogenase, glucose oxidase, and L-lactate oxidase were measured. For the proteins studied the oxidized resonances appeared over a 10.1-ppm range, while the reduced resonances were spread over 10.3 ppm. Reduction caused an upfield shift of about 27 ppm for the free 8-fluoroflavins and most of the 8-fluoro flavoproteins. The notable exception was 8-fluoro-FMN flavodoxin, which was shifted 37.6 ppm, indicating an unusually high electron density in the benzene ring. Ligand binding to the oxidized 8-fluoro flavoproteins caused either upfield or downfield shifts of 1.5–5 ppm, depending on the protein/ligand combination. The 8-fluoro-FAD anthranilate hydroxylase resonance was shifted downfield and split into two peaks in the presence of anthranilate. The 8-fluoro-FMN Old Yellow Enzyme resonance was shifted upfield upon complexation with charge-transfer-forming, para-substituted phenolates. The upfield shift increased from < 1 to 5 ppm as the electron-donating capacity of the phenolate increased. Complexation of native Old Yellow Enzyme with 2,4-difluorophenol caused the fluorine resonances of the ligand to shift and split into two pairs of signals. Each pair of signals was associated with a different isozyme of Old Yellow Enzyme.

Original languageEnglish (US)
Pages (from-to)2670-2679
Number of pages10
JournalBiochemistry
Volume29
Issue number11
DOIs
StatePublished - Mar 1 1990

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ASJC Scopus subject areas

  • Biochemistry

Cite this

Macheroux, P., Kojiro, C. L., Schopfer, L. M., Chakraborty, S., & Massey, V. (1990). 19F NMR Studies on 8-Fluoroflavins and 8-Fluoro Flavoproteins. Biochemistry, 29(11), 2670-2679. https://doi.org/10.1021/bi00463a008