Can free energy transduction be localized at some crucial part of the enzymatic cycle?

Abstract

Our concern here will be with energetic rather than kinetic aspects of how a macromolecular enzyme molecule or enzyme complex in a biological membrane accomplishes the transfer or transduction of one kind of small-molecule free energy into another. An example is the use of the free energy of ATP hydrolysis (to form ADP and P1) to move Ca2+ across a membrane against its own electrochemical potential gradient (Stryer, 1981). In this case, the free energy decreases in the hydrolysis reaction but much of this is recovered in the form of an increase in free energy of the Ca2+ ions (the remainder is dissipated as heat). There is, of course, no net change in the free energy of the enzyme itself (Ca-ATPase).