Amylolysis of a chromogenic substrate, Cibachron Blue F3GA-amylose: kinetics and mechanism.

We compared the modes of action of human pancreatic, human salivary, and porcine pancreatic amylases on Cibachron Blue F3GA-amylose. Both human enzymes showed similar catalytic activity with almost equal Vmax but dissimilar apparent Km's. The ratios of soluble dyed oligosaccharides to reducing substances were identical. Porcine pancreatic amylase exhibited less than half the Vmax of the human enzymes and a smaller apparent Km. Reducing substances were formed faster than were the soluble dyed products. These differences in amylolytic action can be explained by differences in the degree of the "multiple attack" mechanism. Introduction of dye substituents into the amylose molecule did not alter the substrate characteristics of amylose toward human serum amylase.