Difference absorption spectrum of cytochrome c oxidase in the presence of acephate (N-acetyl O,S-dimethyl thiophosphoramide).

The alpha-peak in the difference spectrum between reduced cytochrome c oxidase (cytochrome a and a3) plus acephate (pH 9.5) and oxidized enzyme, shifted from 605 nm to 592 nm. The difference spectrum between reduced cytochrome c oxidase plus acephate (pH 9.5) and the reduced enzyme showed that the alpha and gamma peaks shifted to 592 nm and 432 nm, respectively. The effect of acephate on the spectrum of the reduced cytochrome c oxidase is similar to that of carbon monoxide.