Mitochondrial complex IV, also known as cytochrome C oxidase, is one of the major enzymes in the mitochondrial respiratory chain. It oxidizes the reduced cytochrome C converted from mitochondrial complex III to oxidized cytochrome C and consumes oxygen to generate water. Mitochondrial complex IV can catalyze the oxidation of reduced cytochrome C to oxidized cytochrome C, which has an absorption wavelength at 550 nm. Therefore, the activity of mitochondrial complex IV can be quantified by measure the change OD value at 550 nm.
