Differential Rate Assay of Human Pancreatic and Salivary α-Amylases in Serum Using Two Coupled Enzymes

Publisher Website
Google Scholar
Abstract
p-Nitrophenyl O-6-deoxy-6-[(2-pyridyl)amino]-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-α-D-glucopyranoside (FG5P) is hydrolyzed by human pancreatic α-amylase (HPA) or salivary α-amylase (HSA) to O-6-deoxy-6-[(2-pyridyl)amino]-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-D-glucose (FG3) and p-nitrophenyl α-maltoside or to O-6-deoxy-6[(2-pyridyl)amino]-α-D-glucopyranosyl-(1→4)-O-α-D-glucopyranosyl-(1→4)-O-α-D-glcopyranosyl-(1→4)-D-glucose (FG4) and p-nitrophenyl α-glucoside. The use of α-D-glucosidase (maltase) [EC 3.2.1.20] of Saccharomyces carlsbergensis and oligo-1,6-glucosidase (isomaltase) [EC 3.2.1.10] of bakers' yeast as coupled enzymes differentiates between the two reactions, because α-D-glucosidase liberates p-nitrophenol from both p-nitrophenyl α-glucoside and p-nitrophenyl α-maltoside, but oligo-1,6-glucosidase liberates it only from p-nitrophenyl α-glucoside. HPA produces more FG4 and p-nitrophenyl α-glucoside than HSA. Taking advantage of the differences in the action of the two amylases and in the substrate specificity of the coupled enzymes, we have developed a new colorimetric differential rate assay of α-amylases in human serum.