Electrophoretic and immunological properties of liver alpha-amylase of well-fed and fasted rats.

1. Alpha-Amylase (1,4-alpha-D-glucan glucanohydrolase, EC 3.2.1.1) in the liver of well-fed rats showed a characteristic electrophoretic mobility between those of pancreatic and parotid amylases. Amylase in the liver of fasted rats showed an electrophoretic mobility identical to that of parotid amylase. When fasted rats were re-fed on a standard diet for two days the electrophoretic mobility of their liver amylase returned to that of the liver amylase of well-fed rats. 2. When purified rat pancreatic and parotid amylases were mixed with a final concentration of 4% glycogen solution, their electrophoretic mobilities both became similar to that of liver amylase of well-fed rats. The electrophoretic mobility of glycogen corresponded to that of liver amylase of well-fed rats. Since liver amylase of fasted rats has the same mobility as parotid amylase and serum contains only parotid-type amylase, these findings suggest that liver amylase of well-fed rats may be a complex of serum amylase and glycogen. 3. The antigenicities of the liver amylases of well-fed and fasted rats were the same as that of purified parotid amylase, but different from that of purified pancreatic amylase. Amylase in serum and urine, which had the same electrophoretic mobility as parotid amylase, had the same antigenicity as purified parotid amylase and the liver amylases of well-fed and fasted rats.