PMID:6365921
| Citation |
Kita, K, Konishi, K and Anraku, Y (1984) Terminal oxidases of Escherichia coli aerobic respiratory chain. I. Purification and properties of cytochrome b562-o complex from cells in the early exponential phase of aerobic growth. J. Biol. Chem. 259:3368-74 |
|---|---|
| Abstract |
Cytochrome b562-o complex, a terminal oxidase in the respiratory chain of aerobically grown Escherichia coli K12, was isolated in a highly purified form. The purified oxidase is composed of equimolar amounts of two polypeptides, with Mr = 33,000 and 55,000, determined by gel electrophoresis in the presence of sodium dodecyl sulfate. It contains 19.5 nmol of heme and 16.8 nmol of copper/mg of protein, but no detectable nonheme iron, phospholipid, ubiquinone, or menaquinone. In the difference spectrum at room temperature, the oxidase shows a single alpha absorption peak at 560 nm and at 77 K it shows two alpha absorption peaks at 555 and 562 nm. This oxidase combines with CO and the CO difference spectrum at room temperature has a peak at 416 nm and a trough at 430 nm in the Soret region. Its oxidation-reduction potential is estimated to be 125 mV (pH 7.4) and it is pH-dependent (-60 mV/pH) in medium of pH 6.0 to 7.4. It catalyzes electron transport to oxygen via ubiquinol and ascorbate in the presence of phenazine methosulfate or N,N,N',N'-tetramethyl-p-phenylenediamine dihydrochloride. This oxidase activity depends on phospholipids and is sensitive to respiratory inhibitors, such as 2-heptyl-4-hydroxyquinoline N-oxide, piericidin A, KCN and NaN3. The divalent cations Zn2+, Cd2+, and Co2+ inhibit the oxidase activity extensively. The oxidase activity of the cytochrome b562-o complex was inhibited by photoinactivation with rose bengal, suggesting that the inhibition by zinc ion results from modification of a histidine residue of cytochrome o. |
| Links | |
| Keywords |
Aerobiosis; Carbon Monoxide; Copper/analysis; Cytochrome b Group/isolation & purification; Cytochrome b Group/metabolism; Cytochromes/isolation & purification; Cytochromes/metabolism; Escherichia coli/metabolism; Escherichia coli Proteins; Heme/analysis; Iron/analysis; Kinetics; Molecular Weight; Multienzyme Complexes/isolation & purification; Multienzyme Complexes/metabolism; Oxygen Consumption; Phospholipids/pharmacology; Quinone Reductases/metabolism; Spectrophotometry |
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