Enzymatic Determination of Structure of Singly Branched Hexaose Dextrins Formed by Liquefying α-Amylase of Bacillus subtilis

Abstract

1. Of various branched dextrins formed during digestion of starch with liquefying α-amylase [EC 3. 2. 1. 1] of Bacillus subtilis, a branched dextrin consisting of six glucose units was isolated by paper chromatography and its structure was investigated, in order to obtain a clue to clarify the specificity of the amylase toward branched substrates.
2. The isolated dextrin behaved just as a single dextrin in paper chromatography. It was, however, a mixture of singly branched dextrins of which ramifying positions ty α-l, 6-linkage were different with each other.
3. Investigations using saccharifying α-amylase, β-amylase [EC 3. 2. 1. 2], glucoamylase [EC 3. 2. 1. 3], and pullulanase revealed that the singly branched hexaose dextrins formed by liquefying α-amylase were those having the following structures; 6²-α-maltotriosylmaltotriose, 6²-α-maltosylmaltotetraose, 6³-α-maltosylmaltotetraose.