STRUCTURE OF SODIUM BETA-FLUOROPYRUVATE - GEM-DIOL

Sodium β-fluoropyruvate is shown by X-ray diffraction and infrared spectroscopy to exist as a gem-diol when crystallized from water in the monoclinic space group P21 a. The unit cell dimensions are a = 8.693(1), b = 11.556(1), c = 5.252(1) Å, β = 94.85(8) °. Molecular dimensions of the gem-diol are presented. The carbon-carbon bond to the carboxyl group is long [1.551(2) Å], indicative of a bond that can break easily. The hydration of the carbonyl group is attributed to the high electronegativity of the fluorine atom. While reports exist in the literature of a crystalline form of β-fluoropyruvic acid that contains a carbonyl, rather than a gem-diol group, 13C nmr studies presented here demonstrate that, in aqueous solution, the gem-diol is the predominant (≥95%) form. The significance of these results in the study of the mechanisms of enzymes utilizing pyruvate as a substrate is discussed. If the carbonyl oxygen activity is important for the action of an enzyme, e.g., in the formation of a Schiff base, it is possible that fluoropyruvate may not be a substitute for pyruvate. In other cases the fluoropyruvate can behave as a substrate analog, although its greater bulk may slow down or prevent its entry into the active site. © 1979.