Spontaneous Crystallization of Amylase from Pancreatic Juice of the Rat

Abstract

IN the assay of secretin by Love's method¹ in which pancreatic secretion from the fasted rat is collected in calibrated capillary tubes, it was observed that a slight precipitate very occasionally formed in the tube at room temperature. When the secretion was kept at +2° C. a heavy white deposit almost invariably formed within two days or so which consisted of very fine birefringent needles, often in balls, fans, or sheaves (Fig. 1). The difference in ultra-violet absorption of the secretion before and after formation of the deposit (Fig. 2) suggested that the latter might be a protein. Further experiments showed it to be amylase, and it became of interest to compare its properties with those of crystalline pancreatic α-amylase from human² and pig³.