Reactions and reactivity of myeloperoxidase-derived oxidants: differential biological effects of hypochlorous and hypothiocyanous acids

TY - JOUR

T1 - Reactions and reactivity of myeloperoxidase-derived oxidants

T2 - differential biological effects of hypochlorous and hypothiocyanous acids

AU - Pattison, David I

AU - Davies, Michael Jonathan

AU - Hawkins, Clare Louise

PY - 2012/8

Y1 - 2012/8

N2 - 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.

AB - 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.

KW - Humans

KW - Hydrogen Peroxide

KW - Hypochlorous Acid

KW - Kinetics

KW - Oxidants

KW - Oxidation-Reduction

KW - Oxidative Stress

KW - Peroxidase

KW - Phagocytes

KW - Sulfhydryl Compounds

KW - Thiocyanates

U2 - 10.3109/10715762.2012.667566

DO - 10.3109/10715762.2012.667566

M3 - Journal article

C2 - 22348603

SN - 1071-5762

VL - 46

SP - 975

EP - 995

JO - Free Radical Research

JF - Free Radical Research

IS - 8

ER -