Studies on the Inhibitor Resistant Respiration of the Fungus Myrothecium verrucaria

Abstract

The insensitivity of this fungus to the cytochrome-oxidase inhibitors azide, cyanide, and carbon monoxide was confirmed. Mitochondrial preparations showed the same insensitivities when succinate of a Kreb''s -cycle acid was used as substrate, while the more rapid respiration of cytochrome c was markedly reduced by these inhibitors, although never to a level below that supported by succinate. Spectroscopic studies of the mitochondria at -196[degree] C showed a cytochrome system similar to that of yeast or higher plants, and failed to account for the insensitivities. It is postulated that there are 2 cytochrome-c oxidases present, 1 the normal inhibitor-sensitive cytochrome a + a3, and 1 which is inhibitor-resistant and has not been spectroscopicaly identified.