Calcium binding to the "stone protein" isolated from pancreatic stones of patients with chronic calcified pancreatitis.

Calcium binding to a new secretory protein present in all layers of human pancreatic stones has been studied. This protein with a molecular mass of 13,500 Da has about 4 equivalent binding sites for calcium. Maximum calcium binding was independent of pH and temperature, but the affinity of calcium to this protein increased with decreasing pH and increasing temperature, revealing maximum affinity at pH 7.3 and 37 degrees C. It is concluded that the calcium affinity could explain the presence of the protein in all layers of human pancreatic stones.