Cryogenic absorption spectra of hydroperoxo-ferric heme oxygenase,the active intermediate of enzymatic heme oxygenation |
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Authors: | Denisov Ilia G Ikeda-Saito Masao Yoshida Tadashi Sligar Stephen G |
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Institution: | Department of Biochemistry, University of Illinois, 116 Morrill Hall, 505 S. Goodwin Avenue, Urbana-Champaign, IL 61801, USA. |
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Abstract: | Using radiolysis with (32)P enriched phosphate as an internal source of ionizing radiation, the formation of hydroperoxo-ferric complex from oxy-ferrous precursor with a high yield was monitored at 77 K in heme oxygenase (HO) by means of optical absorption spectroscopy. Well-resolved absorption spectra (maxima at 421 nm, 530 nm, 557 nm) of hydroperoxo-ferric intermediate of this heme enzyme were measured in 70% glycerol/buffer frozen glasses. After annealing at 210-215 K this complex converts to the product complex, alpha-meso hydroxyheme-HO. No heme degradation products were formed in control experiments with ferric HO or other heme proteins. |
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