Abstract
A branching enzyme was extracted from the mycelia of Neurospora crassa, and was purified to electrophortic homogeneity by a procedure including DEAE-Sephacel column chromatography, 6-aminohexyl-Sepharose column chromatography and gel filtration on Toyopearl HW-55S. The subunit molecular weight of this enzyme was estimated to be 80, 000 by electrophoresis in sodium dodecyl sulfate (SDS)-polyacrylamide gel, and 84, 800 by analysis of its amino acid composition and carbohydrate content. The optimum pH of this enzyme was around 8, and the optimum temperature was 27°C. The branching activity of the enzyme was confirmed by its, action on amylopectin and other substrates as well as by the combined action of this enzyme and N. crassa glycogen synthase. Action of this enzyme on various substrates induced decrease in the wave length maximum of absorption spectrum of the glucan-iodine complex, β-amylolysis limit and in the unit chain length of the debranched product. In the combined action, the branching activity stimulated incorporation of glucose into α-glucan. The products formed by the combined action had glycogenlike form, but the unit chain profiles of synthetic products were different from that of the native glycogen on Toyopearl HW-40F.
