Effect of aluminum on calcium binding to bovine intestinal calcium-binding protein

Aluminum is known to inhibit vitamin D-dependent intestinal absorption of calcium. To investigate possible mechanisms of action, the effect of aluminum on the binding of calcium to bovine intestinal calcium-binding protein (CaBP) was studied by means of equilibrium dialysis. The results of these studies indicate that aluminum in concentrations up to 80 microM and up to 80 times the ambient calcium concentration did not significantly alter the affinity of CaBP for calcium (Kd = 0.17 microM) nor its molar capacity (2 mol/mol CaBP).