Occurrence of heme O in photoheterotrophically growing, semi-anaerobic cyanobacterium Synechocystis sp. PCC6803
| Autor: | Bernhard X. Mayer, Susanne Fromwald, Günter A. Peschek, Marnik Wastyn |
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| Rok vydání: | 1995 |
| Předmět: |
Alternative oxidase
Hemeprotein Cytochrome Biophysics Heme group Cytochrome c Group Heme Respiratory electron transport Cyanobacteria Biochemistry Reversed phase HPLC Electron Transport Complex IV chemistry.chemical_compound Structural Biology Genetics Cytochrome c oxidase Anaerobiosis Molecular Biology Chromatography High Pressure Liquid biology Respiratory oxidase Cell Membrane Cell Biology Heme O NAD Cyanobacteria Synechocystis sp. PCC 6803 Heme B Heme A chemistry Spectrophotometry biology.protein |
| Zdroj: | FEBS letters. 371(2) |
| ISSN: | 0014-5793 |
| Popis: | Extraction and identification of the non-covalently bound heme groups from crude membrane preparations of photoheterotrophically grown Synechocystis sp. PCC 6803 by reversed phase high performance liquid chromatography and optical spectrophotometry led to the detection of heme O in addition to hemes B and A which latter was to be expected from the known presence of aa3-type cytochrome oxidase in cyanobacteria. In fully aerated cells (245 microM dissolved O2 in the medium) besides heme B only heme A was found while in low-oxygen cells (10 microM dissolved O2) heme O was present at a concentration even higher than that of heme A. Given the possible role of heme O as a biosynthetic intermediate between heme B and heme A, together with generally much higher Km values of 5-50 microM O2 for oxygenase as compared to Km values of 40-70 nM O2 for typical cytochrome-c oxidase, our findings may permit the conclusion that the conversion of heme O to heme A is an obligately oxygen-requiring process catalyzed by some oxygenase directly introducing oxygen from O2 into the 8-methyl group of heme O. At the same time thus the occurrence of heme O (cytochrome o) in cyanobacteria does of course not imply the existence of an 'alternative oxidase' since according to the well-known 'promiscuity of heme groups' both hemes O and A are likely to combine with one and the same apoprotein. |
| Databáze: | OpenAIRE |
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