Albumin/calcium association at different pH, as determined by potentiometry.

Calcium binding by albumin was determined potentiometrically at physiological ionic strength and temperature as a function of pH. The binding data indicate at least 30 different binding sites with different association constants and different H+ interaction. One site appears to be responsible for the major binding at physiological pH and substance concentration of free calcium, together with three other sites that bind with less affinity.