Vincent S H
Department of Animal and Exploratory Drug Metabolism, Merck Sharp & Dohme Research Laboratories, Rahway, NJ 07065.
Semin Hematol. 1989 Apr;26(2):105-13.
Heme and porphyrins catalyze the formation of various reactive oxygen species under widely different conditions. Porphyrins are potent photosensitizers capable of transferring the energy of their excited state to oxygen, forming 1O2. Heme, by virtue of its iron content, is not a photosensitizer, but it can react with H2O2 forming reactive oxygen intermediates whose nature depends on the oxidation state of the iron. Ferric heme gives rise to a porphyrin cation radical, while ferrous heme catalyzes the formation of OH.. The reactive species formed by heme and porphyrins oxidize susceptible functional groups on protein and lipid components of membranes as well as serum and cytosolic proteins. Oxidation of membrane-bound proteins occurs independently of lipid peroxidation and it is characterized by extensive cross-linking, which takes place subsequent to amino acid oxidation. Serum and cytosolic proteins that bind and may transport heme and porphyrins are of special interest since they can modulate their toxicity by affecting their availability and reactivity. In addition, these proteins are particularly susceptible to oxidation, especially by heme, due to their proximity to the oxidizing species that are formed.
血红素和卟啉在广泛不同的条件下催化各种活性氧的形成。卟啉是强大的光敏剂，能够将其激发态的能量转移给氧，形成单线态氧。血红素由于其含铁量，不是光敏剂，但它可以与过氧化氢反应形成活性氧中间体，其性质取决于铁的氧化态。高铁血红素产生卟啉阳离子自由基，而亚铁血红素催化羟基自由基的形成。血红素和卟啉形成的活性物质氧化膜的蛋白质和脂质成分以及血清和胞质蛋白上的易感官能团。膜结合蛋白的氧化独立于脂质过氧化发生，其特征是广泛的交联，这在氨基酸氧化之后发生。结合并可能转运血红素和卟啉的血清和胞质蛋白特别受关注，因为它们可以通过影响其可用性和反应性来调节其毒性。此外，这些蛋白质特别容易被氧化，尤其是被血红素氧化，因为它们靠近所形成的氧化物质。
