Wirsching P, O'Leary M H
Department of Chemistry, University of Wisconsin--Madison 53706.
Biochemistry. 1988 Feb 23;27(4):1348-55. doi: 10.1021/bi00404a039.
(Z)-3-(Fluoromethyl)phosphoenolpyruvate has been synthesized in nine chemical steps from glyoxylic acid. The compound is stable at pH 3, but at pH 8 it decomposes within seconds to give 2-oxo-3-butenoate. When 3-(fluoromethyl)phosphoenolpyruvate is added to a solution of phosphoenolpyruvate carboxylase or pyruvate kinase, the enzyme is inactivated over the course of an hour. Identical kinetics of inactivation are observed whether the reaction is initiated by addition of 3-(fluoromethyl)-phosphoenolpyruvate, preformed 2-oxo-3-butenoate, or 4-fluoro-2-oxobutanoate (which rapidly undergoes elimination of fluoride ion to form 2-oxo-3-butenoate). The inactivating species in all cases is believed to be 2-oxo-3-butenoate. The inactivation is completely prevented by the presence of dithiothreitol, which reacts rapidly with 2-oxo-3-butenoate. Studies with competitive inhibitors of both enzymes indicate that inactivation does not occur at the active site.
(Z)-3-(氟甲基)磷酸烯醇丙酮酸已由乙醛酸经九个化学步骤合成。该化合物在pH 3时稳定,但在pH 8时会在数秒内分解生成2-氧代-3-丁烯酸酯。当将3-(氟甲基)磷酸烯醇丙酮酸添加到磷酸烯醇丙酮酸羧化酶或丙酮酸激酶溶液中时,酶会在一小时内失活。无论反应是由添加3-(氟甲基)磷酸烯醇丙酮酸、预先形成的2-氧代-3-丁烯酸酯还是4-氟-2-氧代丁酸(其会迅速消除氟离子形成2-氧代-3-丁烯酸酯)引发,都会观察到相同的失活动力学。在所有情况下,失活物质被认为是2-氧代-3-丁烯酸酯。二硫苏糖醇的存在可完全防止失活,二硫苏糖醇能与2-氧代-3-丁烯酸酯快速反应。对这两种酶的竞争性抑制剂的研究表明,失活并非发生在活性位点。