RESUMO
The study of the effect of nucleoside phosphates on the activity of cyanide-resistant oxidase in the mitochondria and submitochondrial particles of Yarrowia lipolytica showed that adenosine monophosphate (5'-AMP, AMP) did not stimulate the respiration of intact mitochondria. The incubation of mitochondria at room temperature (25 degrees C) for 3-5 h or their treatment with ultrasound, phospholipase A, and the detergent Triton X-100 at a low temperature inactivated the cyanide-resistant alternative oxidase. The inactivated alternative oxidase could be reactivated with AMP. The reactivating effect of AMP was enhanced by azolectin. Some other nucleoside phosphates also showed reactivating ability in the following descending order: AMP = GMP > GDP > GTP > MP > IMP. The apparent K(m) values for AMP in reactivation of the alternative oxidase of submitochondrial particles or mitochondria treated with Triton X-100 and incubated at 25 degrees C were calculated. Physiological aspects of activation of the alternative oxidase are discussed in connection with the impairment of electron transfer through the cytochrome pathway.