Ferricyanide, an artificial electron acceptor for hepatic sulfite oxidase (EC 22.214.171.124), has been shown to cause an irreversible inactivation of the enzyme by an interaction at the molybdenum center. The one-electron transferring abilities are lost first, followed by slower parallel losses of oxidase activity and enzymic molybdenum. The rate of inactivation by ferricyanide is lower in the presence of cytochrome c or any of several anions. Accompanying the loss of one-electron transfer activities are changes in the Mo(V) electron paramagnetic resonance signal and in the visible absorption spectrum. Specific degradation of the polypeptide chain takes place subsequently, but at a much slower rate than the inactivation. These results are discussed in relation to the pathways of electron entry, transport and egress in sulfite oxidase. © 1974.
Kessler, D. L., & Rajagopalan, K. V. (1974). Hepatic sulfite oxidase. Identification of the molybdenum center as the site of irreversible inactivation by ferricyanide. BBA - Enzymology, 370(2), 399–409. https://doi.org/10.1016/0005-2744(74)90101-6