Article Abstract:
Research was conducted to prove that an unusual cytochrome o'-type cytochrome c oxidase in a Bacillus cereus cytochrome a3 mutant has a very high affinity for oxygen. Low-temperature ligand exchange methods were used to elucidate the reaction with CO and oxygen of the putative oxidase in membranes of the B. cereus PYM1 mutant. Based on the remarkably high oxygen affinity obtained and the evidence at low temperatures that the cytochrome reacts with oxygen, it is proposed that the cytochrome o'-like pigment is the oxidase responsible for respiratory activity in strain PYM1.
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Article Abstract:
The apparent affinities for oxygen uptake by respiring cells and membranes from mutant without the alternative oxidase cytochrome bo' in Escherichia coli were determined by deoxygenation of oxyleghaemoglobin as a sensitive reporter of dissolved oxygen concentration. Findings indicate that both high-spin haems in the cytochrome bd complex bind CO and show that oxygen can also react with both haems.
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Article Abstract:
Cytochrome measurements and enzyme assays were performed on batch cultures of NH4+-grown Azotobacter vinelandii to study the effect of the rate of O2 supply on the contents of the terminal oxidases cytochromes bd and 'o.' The CO spectra obtained indicated that the content of the cytochrome o-like hemoprotein and that of cytochrome bd are positively regulated by O2 supply.
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