After immunoinhibition with antibodies against human salivary
α-amylase the pancreatic α-amylase is selectively determined
with an enzymatic colorimetric method using the substrate
4,6-ethylidene-p-nitrophenyl-α-D-maltoheptaoside
(ethylidene-G7-PNP).4
Enzymatic colorimetric method using the substrate
4,6-ethylidene-p-nitrophenyl-α-D-maltoheptaoside
(ethylidene-G7-PNP)4 according to the International
Federation of Clinical Chemistry (IFCC).5
The human salivary α-amylase is inhibited by specific
antibodies. The remaining activity of the pancreatic α-amylase
is determined by using the cassette COBAS INTEGRA
α-Amylase EPS Pancreatic and the blocked substrate
4,6-ethylidene-p-nitrophenyl-α-D-maltoheptaoside. The
4,6-ethylidene group on the terminal glucose G7 protects
the substrate against hydrolysis by exoglucosidases. Amylase
hydrolyzes the maltoheptaoside substrate to different
fragments. The G2PNP, G3PNP and G4PNP fragments
so formed are completely hydrolyzed to p-nitrophenol
and glucose by α-glucosidase.
Simplified reaction scheme: