Structures of Multi-Branched Dextrins Produced by Saccharifying α-Amylase from Starch

Abstract

From the digest of β-limit dextrin (prepared from glutinous rice starch) with saccharifying α-amylase of Bacillus subtilis [EC 3.2.1.1] (BSA), two extensively branched dextrins consisting of nine (No. 6,¹ Fig. 1) and ten (No. 7, Fig. 1) glucose units were isolated by paper chromatography. Structural analysis using various enzymes revealed that No. 6 and No. 7 were both mixtures of four triply branched dextrins. They had structures which were built up with 6³-α-glucosylmaltotriose and/or 6²-α-glucosylmaltose as a linking unit. However, the branching configuration and the minimum α-1,4-glucosidic linkages existing between two branches followed one of the three structures shown below: