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.