%0 Journal Article %A Scott, Robert I. %A Edwards, Steven W. %A Chance, Britton %A Lloyd, David %T Terminal Oxidase of Crithidia fasciculata. Reactions with Carbon Monoxide and Oxygen at Subzero Temperatures and Photochemical Action Spectra %D 1983 %J Microbiology, %V 129 %N 7 %P 1983-1989 %@ 1465-2080 %R https://doi.org/10.1099/00221287-129-7-1983 %I Microbiology Society, %X Room temperature CO-difference spectra of whole cells ofCrithidia fasciculata show two CO-reactinghaemoproteins. The reaction of cytochrome a/a 3 with CO is complete within 1 min of bubbling with CO; that of cytochrome b takes longer than 40 min. A non-photodissociable O2-containing compound of cytochrome a/a 3 was formed in whole cell suspensions at −112 °C after photolysis of CO in the presence of 200 μm-O2. No O2-cytochrome b compound was observed under these conditions. Photochemical action spectra for the relief of CO-inhibited respiration, obtained at different O2 tensions, indicate cytochrome a/a 3 to be the major haemoprotein terminal oxidase; no evidence for a b-type cytochrome oxidase has been found. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-129-7-1983