The mechanism of carbohydrase action. 7. Stages in the salivary α-amylolysis of amylose, amylopectin and glycogen

Abstract

The actions of crude saliva and crystalline salivary [alpha]-amylase on starch and maltodextrins were compared, with particular reference to the question whether the [alpha]-amylase hydrolyzes maltotriose. It is concluded that salivary [alpha]-amylase hydrolyzes maltotriose to maltose and glucose. The hydrolysis is activated by Cl and is far slower than that of maltotetraose. By varying the enzyme concentration the salivary [alpha]-amylolysis of amylose can be made to proceed in 2 stages. The first stage, at a low enzyme concentration, is a hydrolysis to maltose and maltotriose. The second stage, with enzyme at 25 times the concentration of that in the first stage, involves the hydrolysis of the maltotriose to glucose and maltose. The [alpha]-amylolysis of amylopectin and glycogen also proceeds in 2 stages. The first-stage products are maltose, maltotriose and branched [alpha]-limit dextrins, ranging from a pentasaccharide upwards. The second-stage products are glucose, maltose and [alpha]-limit dextrins, of which the smallest is a tetrasaccharide.