The purification and identification of a phospholipid activated cytochrome C4:O terminal oxidase from Azotobacter vinelandii

Journal Title
Journal ISSN
Volume Title

The membrane-bound cytochrome oxidase of Azotobacter vinelandii was solubilized by Triton X-100 and KC1, and further resolved into two components, by DEAE-cellulose chromatography. Two fractions (I & V) were required for maximum TMPD oxidase turnover. Fraction V, the major hemoprotein component, contained both the c-type cytochrome c4 (3.6 nmoles/mg protein) and cytochrome o (1.6 nmoles/mg protein), and was capable of carrying out moderately high TMPD oxidase activity. Fraction I, a greenish-yellow lipoprotein fraction, which contained primarily phosphatidyl ethanol amine with some phosphatidylglycerol, exhibited no TMPD oxidase activity. When Fraction I was preincubated with Fraction V, a 2-4 fold stimulation in TMPD oxidase activity occurred. This activation was noted even when Fraction I was boiled. This remarkable heat stable activation effect suggested that a micellar phospholipids activated TMPD oxidation in A. vinelandii. This phospholipid activation phenomenon is similar to that commonly observed for the mitochondrial cytochrome a+a3 oxidase. [...]

Cytochrome oxidase