Studies on carbohydrate-metabolising enzymes. Part XX. Sweet-corn debranching enzymes

Extracts of sweet corn contain a mixture of debranching enzymes which have been separated to give a typical R-enzyme (which acts only on amylopectin) and an isoamylase (which acts on both glycogen and amylopectin). The action of isoamylase on phytoglycogen gives a mixture of maltosaccharides and a residual polysaccharide which had a glycogen rather than an amylopectin-type structure. This suggests that, in vivo, amylopectin is not formed by the enzymic debranching of a glycogen precursor. Sweet-corn extracts also contain a third a-(1?6)-glucosidase which hydrolyses pullulan. © 1969.