Institute of Applied Radiation Chemistry, Faculty of Chemistry, Technical University of Lodz, Wroblewskiego 15, 93-590 Lodz, Poland.
Free Radic Res. 2010 Feb;44(2):217-23. doi: 10.3109/10715760903406113.
The kinetics of the reaction of lactoperoxidase with peroxynitrite was studied under neutral and acidic pH. Lactoperoxidase catalyses peroxynitrite decay with the rate constant, k(c), increasing with decreasing pH. The values of k(c) obtained at pH 7.1, 6.1 and 5.1 are (1.9+/-0.1)x10(6), (5.0+/-0.1)x10(6) and (8.5+/-0.2)x10(6) M(-1)s(-1), respectively. This tendency means that peroxynitrous acid is the species involved in the reaction with the catalytic centre of lactoperoxidase. Lactoperoxidase is also able to scavenge peroxynitrite in the presence of bicarbonate with the rate constant identical, within experimental error, to that measured in the absence of bicarbonate. It is thus concluded that CO(3)-(.)/(.)NO(.2) radicals formed in the system do not inactivate LPO. The mechanism of the catalytic scavenging of peroxynitrite by LPO is proposed. The physiological relevance of this reaction is discussed.
研究了中性和酸性 pH 条件下乳过氧化物酶与过氧亚硝酸盐反应的动力学。乳过氧化物酶催化过氧亚硝酸盐的衰减，其速率常数 k(c)随 pH 值的降低而增加。在 pH 值为 7.1、6.1 和 5.1 时，k(c)的值分别为(1.9+/-0.1)x10(6)、(5.0+/-0.1)x10(6)和(8.5+/-0.2)x10(6)M(-1)s(-1)。这种趋势意味着过氧亚硝酸是与乳过氧化物酶催化中心反应的物种。在碳酸氢盐存在的情况下，乳过氧化物酶也能够清除过氧亚硝酸盐，其速率常数在实验误差范围内与没有碳酸氢盐时测量的值相同。因此，可以得出结论，在该系统中形成的 CO(3)-(.)/(.)NO(.2)自由基不会使 LPO 失活。提出了 LPO 催化清除过氧亚硝酸盐的机制。讨论了该反应的生理相关性。
