Interaction of human α-amylases with inhibitors from wheat flour

Abstract

The interaction of four purified α-amylase (1,4-α- d-glucan glucanohydrolase, EC 3.2.1.1) inhibitors with human salivary and pancreatic α-amylases was investigated. The inhibitory activity of the four proteins towards salivary α-amylase was significantly increased by pre-incubation of the enzyme with inhibitor before adding substrate. This effect was not observed with the inhibition of pancreatic α-amylase by inhibitors 1 and 2. Inhibition of both amylases was affected to different degrees by incubating starch with inhibitor prior to the addition of enzyme. Maltose, at concentrations which only slightly affected amylase activity, prevented the inhibition of both enzymes by all four inhibitors. Gel filtration studies on salivary amylase-inhibitor mixtures showed the formation of EI complexes on a mol-to-mol ratio. A similar complex between pancreatic α-amylase and inhibitor 4 was observed, though complex formation between pancreatic α-amylase and the other inhibitors was not clearly demonstrated.