Eiserich J P, Butler J, van der Vliet A, Cross C E, Halliwell B
Department of Internal Medicine, University of California, Davis, 95616, USA.
Biochem J. 1995 Sep 15;310 ( Pt 3)(Pt 3):745-9. doi: 10.1042/bj3100745.
By utilizing a pulse-radiolytic technique, we demonstrate for the first time that the rate constant for the reaction of nitric oxide (.NO) with biologically relevant tyrosine and tryptophan radicals (Tyr. and Trp. respectively) in amino acids, peptides and proteins is of the order of (1-2) x 10(9) M-1.s-1. We also show that .NO effectively interferes with electron-transfer processes between tryptophan and tyrosine residues in proteins subjected to pulse radiolysis. The near diffusion-controlled rates of these reactions, coupled with the increasingly recognized role of protein radicals in enzyme catalysis and oxidative damage, suggest that Tyr. and Trp. are likely and important targets for .NO generated in vivo.
通过利用脉冲辐射分解技术,我们首次证明,在氨基酸、肽和蛋白质中,一氧化氮(·NO)与具有生物学相关性的酪氨酸和色氨酸自由基(分别为Tyr·和Trp·)反应的速率常数约为(1 - 2)×10⁹ M⁻¹·s⁻¹。我们还表明,·NO能有效干扰脉冲辐射分解作用下蛋白质中色氨酸和酪氨酸残基之间的电子转移过程。这些反应接近扩散控制的速率,再加上蛋白质自由基在酶催化和氧化损伤中日益被认可的作用,表明Tyr·和Trp·很可能是体内产生的·NO的重要作用靶点。