Heme proteins from myeloperoxidase

By oxidation with copper or hypochlorous acid, HDL loses its ability to remove cholesterol from cultured cells. This effect would be expected to be detrimental and promote cardiovascular disease. In contrast, however, HDL becomes more effective in protecting mice against atherosclerosis by exposing it to tyrosyl radicals generated by myeloperoxidase, a heme protein seereted by macrophages in human atherosclerotic lesions. The resulting tyrosylated HDL... 

Myeloperoxidase is the principal heme protein of the mammalian neutrophil functioning in the phagocytic process through its capacity at acid pH to peroxidize chloride ions to hypochlorous acid. Investigations of the structure of myeloperoxidase from various species have shown it to be a two-heme protein with a molecular weight in the region 135,000-150,000 (Agner, 1958, 1970 Harrison and Schultz, 1976 Harrison et al, 1977). 

Figure 16-12 Linkage of heme to mammalian peroxidases. There are two ester linkages to carboxylate side chains from the protein.220 221 Myeloperoxidase contains a third linkage.222 2223...

Figure 9 Structure of myeloperoxidase (MPO) along with the heme environment as observed in the high-resoiution crystal stmcture. (This figure was generated from coordinates of ICXP deposited in the Protein Data Banlr)...

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