Enzymatic Debranching of Starches from Maize of Various Genotypes in High Concentration of Dimethylsulphoxide

The activity of two debranching enzymes has been studied in DMSO/water mixtures, using waxymaize starch as a substrate. Action was unaffected in digests containing up to 40% of DMSO for Pseudomonas isoamylase and 20% for Enterobacter aerogenes pullulanase. When normal maize was submitted to isoamylase action in 40% DMSO, the polysaccharide was completely debranched. In contrast, a water insoluble polysaccharide, amylomaize, under these conditions, still contained some branched material, tentatively attributed to the presence of α‐maltosyl stubs on the branched intermediate fraction. The results show that these debranching enzymes can be used in dimethylsulphoxide solution to study the fine structure of water‐insoluble, highly branched polysaccharides.