Formation of reactive halide species by myeloperoxidase and eosinophil peroxidase.
The formation of chloro- and bromohydrins from 1-palmitoyl-2-oleoyl-sn-glycero-3-phosphocholine following incubation with myeloperoxidase or eosinophil peroxidase in the presence of hydrogen peroxide, chloride and/or bromide was analysed by matrix-assisted laser desorption/ionisation time-of-flight mass spectrometry. These products were only formed below a certain pH threshold value, that increased with increasing halide concentration. Thermodynamic considerations on halide and pH dependencies of reduction potentials of all redox couples showed that the formation of a given reactive halide species in halide oxidation coupled with the reduction of compound I of heme peroxidases is only possible below a certain pH threshold that depends on halide concentration. The comparison of experimentally derived and calculated data revealed that Cl(2), Br(2), or BrCl will primarily be formed by the myeloperoxidase-H(2)O(2)-halide system. However, the eosinophil peroxidase-H(2)O(2)-halide system forms directly HOCl and HOBr.
Spalteholz
Holger
H
Institute of Medical Physics and Biophysics, University of Leipzig, Haertelstr. 16-18, 04107 Leipzig, Germany.
Panasenko
Oleg M
OM
Arnhold
Juergen
J
D000438:Alcohols / Q000138:chemical synthesis*; D002728:Chlorohydrins / Q000138:chemical synthesis*; D003198:Computer Simulation; D047209:Eosinophil Peroxidase / Q000737:chemistry*; D006219:Halogens / Q000138:chemical synthesis; D006861:Hydrogen Peroxide / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D008956:Models, Chemical; D010084:Oxidation-Reduction; D009195:Peroxidase / Q000737:chemistry*; D010713:Phosphatidylcholines / Q000737:chemistry*; D013816:Thermodynamics
D000438:Alcohols; D002728:Chlorohydrins; D006219:Halogens; D010713:Phosphatidylcholines; C023963:bromohydrins; D006861:Hydrogen Peroxide; D047209:Eosinophil Peroxidase; D009195:Peroxidase; C028694:1-palmitoyl-2-oleoylphosphatidylcholine