Abstract
A 74 year-old patient with macroamylasemia is reported. His urinary amylase level was normal whereas serum amylase level was persistently and slightly elevated, and the ratio of the amylase to creatinine clearance ratio was decreased to 0.81%.
On the serum amylase isozyme pattern, a broad band migrating from the position where normal pancreatic amylase was stained to the anode was disclosed.
On Sephadex G-200 gel filtration, an abnormal amylase peak corresponding to 7S as well as an additional abnormal broad amylase activity from 7S to the fraction where normal amylase is usually eluted, were detected.
A normal peak of amylase activity was eluted from a Bio-Gel A-0.5m column, suggesting dissociation of amylase protein from binding substances in the serum.
The amylase fraction and the protein fraction containing the binding substances which were dissociated each other by Sephadex G-200 gel filtration at pH 3.4 were combined in vitro and resulted in the regeneration of the macroamylase. Furthermore a mixture of the dissociated protein fraction and normal pancreatic or salivary amylase was disclosed to produce macroamylase.
No binding between amylase and immunoglobulins, albumin or α1-antitrypsin was suggested by amylase staining after immunoelectrophoresis and immunoprecipitations by mono-specific anti-sera.
Amylase and binding substances in the present case were completely dissociated by 5M Urea treatment or Bio-Gel A-0.5 m gel filtration at pH 8.0, but not by Triton X-100 treatment, concluding that they were dound each other by weak hydrogen bonds.
