Terminal enzymeof the mitochondrial respiratory chain and catalyzes over 95% of oxygenmetabolism. CCO has an absorption peak in the middle of the near infraredregion, and it can therefore be measured using NIRS and used as a non-invasivemarker of changes in mitochondrial oxygen consumption and utilization (ratherthan hemoglobin that is only going to tell us about the carriage of oxygen inthe blood).
See Chromophores, Hemoglobin, Optical imaging, Functional near-red spectroscopy