Crystallization and preliminary X-ray analysis of Thermoactinomyces vulgaris R-47 maltooligosaccharide-metabolizing enzyme homologous to glucoamylase.

A maltooligosaccharide-metabolizing enzyme from Thermoactinomyces vulgaris R-47 (TGA) homologous to glucoamylase degrades maltooligosaccharides more efficiently than starch, unlike fungal glucoamylases. TGA was crystallized and the state of the protein in solution was analyzed by gel-filtration chromatography. Diffraction data were collected to 3.31 A resolution. The TGA crystal belongs to the orthorhombic space group P2(1)2(1)2(1) or P2(1)2(1)2, with unit-cell parameters a = 110.2, b = 317.6, c = 144.9 A, and is expected to contain five to eight TGA molecules per asymmetric unit. Gel-filtration and native PAGE analyses indicated that TGA exists as a dimer in solution. This is the first report of the crystallization of an oligomeric glucoamylase.