%0 Journal Article %A Edwards, C. %A Chance, B. %T Evidence for the Presence of Two Terminal Oxidases in the Trypanosomatid Crithidia oncopelti %D 1982 %J Microbiology, %V 128 %N 7 %P 1409-1414 %@ 1465-2080 %R https://doi.org/10.1099/00221287-128-7-1409 %I Microbiology Society, %X Increasing concentrations of cyanide inhibited the respiration of whole cells of Crithidia oncopelti in a biphasic fashion. Approximately 80% inhibition was attained with 40 μm-KCN. No further inhibition occurred until the concentration of KCN reached approximately 200 μm. Thereafter inhibition rose gradually to 100% at 1500 μm-KCN. Difference spectra revealed the presence of two CO-reacting haemoproteins. These were shown to be two different functional oxidases by photochemical action spectra obtained by using laser light. One oxidase was identified as cytochrome a+a 3 whilst the other had the properties of cytochrome o. Both oxidases could be detected in cells at all stages of growth by the above methods. %U https://www.microbiologyresearch.org/content/journal/micro/10.1099/00221287-128-7-1409