title: Detection of glycogen-debranching system in trophozoites of Entamoeba histolytica.
abstract: Homogenates of trophozoites of Entamoeba histolytica were shown to bring about the total degradation of glycogen while purified phosphorylase of the same source alone yielded a limit dextrin as end product. An enzyme system capable of debranching the limit dextrin was obtained from the 40,000 g pellet by extraction in aqueous medium, purified by gel filtration on Fractogel TSK HW-55(F), and separated from phosphorylase by chromatography on Blue Sepharose CL-6B and aminobutyl Agarose. The glycogen-debranching system was purified 540-fold to a state of homogeneity by criterion of disc-gel electrophoresis. The purified enzyme was able to degrade glycogen-limit dextrin in the presence of phosphorylase and exhibited activities of both amylo-1,6-glucosidase (EC 3.2.1.33) and 4-alpha-glucanotransferase (EC 2.4.1.25). Although amylo-1,6-glucosidase released glucose from a glycogen-phosphorylase limit dextrin, transferase activity moved single glucose residues from the limit dextrin to 4-nitrophenyl-alpha-glucoside yielding successively 4-nitrophenyl-alpha-maltoside and 4-nitrophenyl-alpha-maltotrioside that could be detected by HPLC. Native glycogen-debranching system exhibited a relative molecular mass of Mr = 180,000 +/- 10% by gel filtration and gel electrophoresis in both denaturing and nondenaturating conditions.
authors.affiliation: Fachbereich Biologie/Chemie, Universität Osnabrück, Abteilung Biochemie, Federal Republic of Germany.
authors.forename: E
authors.initials: E
authors.lastname: Werries
authors.forename: A
authors.initials: A
authors.lastname: Franz
authors.forename: S
authors.initials: S
authors.lastname: Geisemeyer
mesh_terms: D000818:Animals; D002384:Catalysis; D004748:Entamoeba histolytica / Q000201:enzymology*; D006003:Glycogen / Q000378:metabolism; D006004:Glycogen Debranching Enzyme System / Q000032:analysis* / Q000378:metabolism; D010762:Phosphorylase a / Q000032:analysis
chemical_list: D006004:Glycogen Debranching Enzyme System; D006003:Glycogen; D010762:Phosphorylase a