Partial purification and characterization of a soluble haemoprotein, having spectral properties similar to cytochrome a1, from anaerobically grown Escherichia coli

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Abstract
‘Soluble’ fractions obtained after high‐speed differential centrifugation of extracts from ultrasonically disrupted Escherichia coli, grown anaerobically with glycerol and fumarate, contain at least two haemoproteins, distinguishable by their CO‐binding characteristics. Reduced minus oxidized spectra show a maximum at 598 nm and a shoulder to the Soret region near 440 nm, features generally attributed to ‘cytochrome a 1’. CO‐reduced minus reduced difference spectra show the more rapidly CO‐binding component to have a trough at 444 nm, also generally attributable to an a‐type cytochrome. The partially purified a 1‐like component has catalase and peroxidase activities, and lacks copper. An appropriate nomenclature for the a 1‐like haemoprotein and its similarity to catalase are discussed.