CALDECRIN PREFORM REQUIRES TRYPSIN ACTIVATION FOR THE ACQUISITION OF SERUM CALCIUM-DECREASING ACTIVITY

Preform serum calcium-decreasing factor (procaldecrin) was purified fr om porcine pancreas acetone powder. Procaldecrin showed chymotrypsin a ctivity after trypsin treatment in a time- and dose-dependent manner. Procaldecrin did not possess serum calcium-decreasing activity but acq uired serum calcium-decreasing activity as well as protease activity a fter trypsin treatment. However, PMSF treatment after activation of pr ocaldecrin by trypsin did not affect the serum calcium-decreasing acti vity, even though protease activity was nullified by treatment with PM SF. These findings suggest that the serum calcium-decreasing activity acquired by procaldecrin requires conformational change caused by tryp sin treatment.