Effects of Ethylene, Carbon Dioxide, and Ethylene – Carbon Dioxide Mixtures on the Activities of "Membrane-Containing" and "Highly Purified" Preparations of Adenosine Triphosphatase from Pea-Cotyledon Mitochondria

Abstract

From pea-cotyledon mitochondria two types of adenosine triphosphatase (ATP phosphohydrolase) were prepared, "membrane-bound" and "highly purified." Activities of both enzyme preparations were dependent on Mg2+ and were stimulated by Na+ and K+. Ethylene had no effect on the activity of either the "membrane-bound" or the "highly purified" enzyme. Ethylene – carbon dioxide – air mixtures stimulated the activity of the "membrane-bound" but not the "highly purified" ATPase, when Na+ and K+ were present. When these ions were absent, the gas mixture greatly increased the activities of both enzyme preparations. The work shows a direct action of ethylene on an enzyme (mitochondrial ATPase), its dependence on the presence of certain levels of CO2, and the augmentation of the ethylene–CO2 effects by the presence of phospholipids.