Inhibition of anion transport across the red cell membrane by dinitrophenylation of a specific lysine residue at the H2DIDS binding site of the band 3 protein

The mechanism of free energy coupling in active transport is discussed with special reference to the sarcoplasmic reticulum Ca²⁺-ATPase. In the current working schemes for cation transport ATPases, free energy transduction is nearly always based on enzyme conformational changes. The principal objective of the present article is to examine whether recent experimental results on Ca²⁺-ATPase may in fact be better explained by assuming the existence of a direct chemiosmotic process. In the scheme proposed, free energy transduction between ATP and calcium is based on a transfer of solvation water between the acylphosphate bond and the bound calcium ions.