Specific assay of alpha-dextrin 6-glucanohydrolase using labeled pullulan.

A new method was developed for the assay of alpha-dextrin 6-glucanohydrolase (EC 3.2.1.41), which hydrolyzes the alpha-D (1----6) glucosidic bonds occurring in polyglucans such as pullulan and amylopectin limit dextrins. After enzymatic hydrolysis of a pullulan-dye conjugate, the remaining substrate is precipitated by adding ethanol. Colored reaction products are determined by measuring the supernatant absorbance at 534 nm. The assay is simple, specific, and suitable for both plant and bacterial enzymes.