A detection method of α-amylase activity after two-dimensional electrophoresis was described. An agar-containing filter paper was overlaid on a slice (2mm in thickness) of a slab gel after two-dimensional electrophoresis. Then a 1mm thick blue starch polymer-containing Sepharose layer was overlaid on the ager-filter paper and kept at 37°C. As α-amylase was detected on the filter paper, the filter paper was dried up and densitometry was easy performed. Further, the stained spots on the filter paper did not decolorize after 6 months' preservation.
Human body fluid samples (5 sera, 2 salivas, 1 pancreatic juice, and 1 urine) were subjected to the activity staining method. Two to six activity spots of α-amylase were detected. The spots were classified into four main species by their isoelectric points; pI 6.9, pI 6.5, pI 5.9, and pI 5.3. The molecular weights of the spots ranged from 140, 000 to 500, 000.