Stimulations of oxygen uptake by electron transfer inhibitors.

The stimulation of oxygen uptake induced in avocado tissue slices by amytal, azide and cyanide has been studied. The effects of these inhibitors on O(2) uptake and on phosphorylation suggest the coexistence of phosphorylating and non-phosphorylating electron transfer systems in the fruit. The reason for the stimulations of O(2) uptake is believed to be the result of an increased supply of a limiting cofactor to the phosphorylating sites. The increased availability of cofactor per site is due to the inhibition of part of the cytochrome chain and the consequent reduction in the number of active phosphorylating sites.