The Heart Research Institute , 7 Eliza Street, Newtown, Sydney, NSW 2042, Australia.
Free Radic Res. 2012 Aug;46(8):975-95. doi: 10.3109/10715762.2012.667566. Epub 2012 Apr 23.
Myeloperoxidase (MPO) is recognised to play important roles both in the immune system and during the development of numerous human pathologies. MPO is released by activated neutrophils, monocytes and some tissue macrophages, where it catalyses the conversion of hydrogen peroxide to hypohalous acids (HOX; X = Cl, Br, SCN) in the presence of halide and pseudo-halide ions. The major reactive species produced by MPO under physiological conditions are hypochlorous acid (HOCl) and hypothiocyanous acid (HOSCN), with the ratio of these oxidants critically dependent on the concentration of thiocyanate ions (SCN⁻). The reactivity and selectivity of HOCl and HOSCN for biological targets are markedly different, indicating that SCN⁻ ions have the potential to modulate both the extent and nature of oxidative damage in vivo. This article reviews recent developments in our understanding of the role of SCN⁻ in modulating the formation of MPO-derived oxidants, particularly in respect to the differences in reaction kinetics and targets of HOCl compared to HOSCN and the ability of these two oxidants to induce damage in biological systems.
髓过氧化物酶（MPO）在免疫系统和多种人类病理的发生发展中发挥着重要作用。MPO 由激活的中性粒细胞、单核细胞和一些组织巨噬细胞释放，在卤化物和拟卤化物离子存在下，它催化过氧化氢转化为次卤酸（HOX；X=Cl、Br、SCN）。在生理条件下，MPO 产生的主要活性物质是次氯酸（HOCl）和次硫氰酸（HOSCN），这些氧化剂的比例取决于硫氰酸根离子（SCN⁻）的浓度。HOCl 和 HOSCN 对生物靶标的反应性和选择性明显不同，表明 SCN⁻离子有可能调节体内氧化损伤的程度和性质。本文综述了近年来人们对 SCN⁻在调节 MPO 衍生氧化剂形成中的作用的认识的最新进展，特别是在 HOCl 与 HOSCN 的反应动力学和靶标差异以及这两种氧化剂在生物系统中诱导损伤的能力方面。
