| Abstract: | The effects of hydrazine on ferrocytochrome c oxidation by cytochrome oxidase and on spectral properties of the enzyme were studied. Hydrazine was found to modify the spectral properties of lipid-depleted preparations of cytochrome oxidase dissolved in 1% cholate and to inhibit the cytochrome c oxidase activity of the enzyme, whereas the kinetic properties of lipid-enriched and Tween preparations were unchanged by hydrazine. Cytochrome oxidase was found to possess a hydrazine oxidase activity. This activity was not coupled with the specific cytochrome c oxidase activity. The effect of pH on the observed changes was studied. Hydrazine was found to yield protein bands in the optical spectra of cytochrome oxidase as 580 nm, 537 nm and 845 nm. It is concluded that hydrazine interacts with the oxygen-binding site of cytochrome oxidase. The effect of hydrazine on the formation of the "ferryl" form (Fe4+a3/Cu2+b) of the enzyme is discussed. |
