Blessinger K J, Tunnicliff G
Laboratory of Neurochemistry, Indiana University School of Medicine, Evansville 47712.
Biochem Cell Biol. 1992 Aug;70(8):716-9. doi: 10.1139/o92-109.
3-Bromopyruvate inhibited 4-aminobutyrate aminotransferase (EC 2.6.1.19) from Pseudomonas fluorescens, apparently irreversibly. Kinetics of this inactivation were studied by continuously monitoring the enzyme reaction at 30 degrees C in the presence of inhibitor. Irrespective of how high an inhibitor concentration was present, a maximum rate of inactivation was eventually achieved (5.9 x 10(-3) s-1), indicating the formation of a reversible inhibitor-enzyme complex before the final inactivation step. The dissociation constant of this complex was found to be 6.5 microM. This affinity labelling by 3-bromopyruvate suggests the presence of essential sulphydryl groups on the enzyme, since this compound is known to preferentially alkylate cysteinyl residues.
3-溴丙酮酸对荧光假单胞菌的4-氨基丁酸转氨酶（EC 2.6.1.19）具有明显不可逆的抑制作用。通过在30℃下在抑制剂存在的情况下连续监测酶反应来研究这种失活的动力学。无论存在多高的抑制剂浓度，最终都会达到最大失活速率（5.9×10⁻³ s⁻¹），这表明在最终失活步骤之前形成了可逆的抑制剂-酶复合物。发现该复合物的解离常数为6.5微摩尔。3-溴丙酮酸的这种亲和标记表明该酶上存在必需的巯基，因为已知该化合物优先使半胱氨酰残基烷基化。
