Cyanide-insensitive respiration of Candida lipolytica

Whole cells of the yeast Candida lipolytica exhibited a high, cyanide-sensitive endogenous respiration which became completely cyanide-insensitive under certain physiological circumstances namely (1) in the stationary phase of growth and (2) upon aeration in the resting state. This cannot be due to a change in permeability of the cell wall as the respiration of protoplasts showed the same (in)sensitivity to cyanide as the cells from which they were obtained.The cyanide-insensitive respiration of C. lipolytica was located in the mitochondria and coexisted with the normal respiratory chain, as the mitochondria isolated from cyanide-insensitive cells exhibited at the same time a cyanidesensitive respiration of ascorbate and N,N,N,N-tetramethyl-p-phenylenediamine and a cyanide-insensitive respiration of succinate.The alternate respiratory pathway was sensitive to benzyl- and salicylhydroxamic acids. In this respect it resembles the alternate mitochondrial pathway described in the literature for various plants.The cyanide-insensitive respiration did not appear in the resting state when the cells were aerated in the presence of cycloheximide nor at 0 C instead of at room temperature. These facts suggest some form of induction involving new protein synthesis. The induction process depends on the presence of molecular oxygen as the cyanide-insensitive endogenous respiration did not appear during agitation of yeast cells in the resting state if the gaseous atmosphere lacked oxygen.