Studies on starch-degrading enzymes : Part XII. The initial stages of the action on amylose of the alpha-amylases from B. subtilis, human saliva, malted rye, and porcine pancreas☆

Abstract The action pattern on amylose of the alpha-amylases from B. subtilis , human saliva, malted rye, and porcine pancreas has been studied. In the initial stages, the reaction has been followed by measuring the weight-average degree-of-polymerization ( DP w ) by viscometry, and also the number-average value ( DP n ) by enzymic assay. The mode of enzymic hydrolysis was established by following changes in the value of the ratio DP w / DP n , and also by chromatographic examination of the products of low molecular weight. We have confirmed that the porcine, pancreatic alpha-amylase is unique amongst those enzymes examined, in showing evidence of multiple attack at certain pH-values, and have shown that the presence of glycerol (40%, v/v) changes the mode of action in the initial stages to an essentially random form. The significance of this finding is discussed.