Effect of pH on interaction of calcium ions with serum proteins

¹ Department of Physiology, Stanford University, Stanford, California

A study has been made of the effect of pH on the dissociation of calcium proteinate in rabbit serum. Equations were derived from the experimental data which define a) the effect of serum pH on the McLean-Hastings dissociation constant for the dissociation of calcium proteinate; b) the relationship between the serum pH and the concentration of calcium which is ultrafiltrable; c) the effects of pH, total protein, and total calcium concentration on the change in calcium ion concentration (ultrafiltrable calcium) per unit change in pH. A simple, linear equation was derived from the data which gives serum ultrafiltrable calcium concentration in terms of pH, total protein, and total calcium concentration. A similar study on the dissociation of calcium proteinate was made on purified bovine serum albumin. The results obtained with this system were similar to those obtained on rabbit serum, but the scattering of the data in the case of the purified protein system was far less pronounced. The data on purified albumin was used to re-examine some of the relationships which were derived from the data on rabbit serum.