Column-Chromatographic Studies of Isoamylases in Human Serum, Urine, and Milk

Pancreatic and salivary isoamylases not discerned by a chromatographic method previously described have been detected by a modification of that method. Detailed analysis of the nature of these isoamylases and their distribution showed that the pancreatic type (P-type) and salivary type (S-type) isoamylases in pancreatic extract and saliva appear in normal urine along with an isoamylase of unknown origin (X-type). Normal serum could not be similarly studied because of the low amylase activity in such serum. However, the X-type isoamylase fraction was found in three hyperamylasemic sera, including one from a patient with lung carcinoma who produced S-type amylase. Study of 25 samples of human milk revealed high amylase activity and no detectable P-type; S-type components were found along with the X-type component. Parallel patterns of variation were found in human milk in two patients studied for six months postpartum. Salivary amylase and the S-type amylase in milk and in the serum of the patient with lung carcinoma and marked hyperamylasemia appeared to be similar, and may be identical.