[Mechanism of energy transduction in Na+, K+-ATPase]

The author reviews the molecular properties of Na+, K+-ATPase not only to elucidate the reaction sequence of the enzyme, but also to obtain a better understanding of the mechanism of energy transduction. It is shown that the reaction sequence which had been proposed mainly from phosphorylation kinetics has now been proven by the direct measurement of dynamic fluorescence changes during the hydrolysis of ATP. The formation of MgNaE1 ATP and the transition of NaE1P to E2P accompany the largest fluorescence changes in both the intrinsic and the extrinsic probes, respectively. These findings seem to be a useful step for understanding the mechanism of energy transduction in Na+, K+-ATPase.