Figure 5.

Phase II: Ca²⁺/Mg²⁺ Transport. (A) Free energy released from ATP hydrolysis by E-NTPase on the outer membrane surface would yield -7.3 kcal mol^-1 or by formation of AMP by E-NTPDase would yield -10.9 kcal mol^-1. (B) The energy is utilized for opening the channel formed by the E-NTPase/E-NTPDase, by altering the conformation of the sensors. This altered conformation has an inherent channel-opening effect; loss of the energy source causes the sensors to revert to the resting state, which corresponds to channel closing.