Zaki L, Julien T
Biochim Biophys Acta. 1985 Sep 10;818(3):325-32. doi: 10.1016/0005-2736(85)90006-9.
Phenylglyoxal is found to be a potent inhibitor of sulfate equilibrium exchange across the red blood cell membrane at both pH 7.4 and 8.0. The inactivation exhibits pseudo-first-order kinetics with a reaction order close to one at both pH 7.4 and 8. The rate constant of inactivation at 37 degrees C was found to be 0.12 min-1 at pH 7.4 and 0.19 min-1 at pH 8.0. Saturation kinetics are observed if the pseudo-first order rate constant of inhibition is measured as a function of phenylglyoxal concentration. Sulfate ions as well as chloride ions markedly decrease the rate of inactivation by phenylglyoxal at pH 7.4, suggesting that the modification occurs at or near to the binding site for chloride and sulfate. The decrease of the rate of inactivation produced at pH 8.0 by chloride ions is much higher than that produced by sulfate ions. Kinetic analysis of the protection experiments showed that the loaded transport site is unable to react with phenylglyoxal. From the data it is concluded that the modified amino acid(s) residues, presumably arginine, is (are) important for the binding of the substrate anion.
苯乙二醛被发现是红细胞膜上硫酸盐平衡交换的强效抑制剂，在pH 7.4和8.0时均如此。失活表现出假一级动力学，在pH 7.4和8时反应级数均接近1。在37℃时，pH 7.4下失活的速率常数为0.12 min⁻¹，pH 8.0下为0.19 min⁻¹。如果将假一级抑制速率常数作为苯乙二醛浓度的函数进行测量，则观察到饱和动力学。硫酸根离子和氯离子在pH 7.4时均显著降低苯乙二醛的失活速率，这表明修饰发生在氯离子和硫酸根离子的结合位点处或其附近。氯离子在pH 8.0时产生的失活速率降低远高于硫酸根离子。保护实验的动力学分析表明，负载的转运位点无法与苯乙二醛反应。从这些数据可以得出结论，修饰的氨基酸残基，可能是精氨酸，对于底物阴离子的结合很重要。
