title: Inactivation and thermal stabilization of glycogenin by linked glycogen.
abstract: Glycogen-free but not glycogen-bound glycogenin transglucosylates dodecyl-beta-maltoside. Furthermore, its sugar nucleotide-binding site can be photoaffinity labeled using [beta-(32)P]5-azido-UDP-glucose. Disruption with DMSO of the hydrogen bonds that stabilize the alpha-helical structure of glycogen restored the photoaffinity labeling of the glycogen-bound enzyme but not its transglucosylation activity. The larger size polysaccharide that linked to glycogenin allowed transglucosylation corresponding to that of PG-200, a proteoglycogen species of M(r) 200 kDa. PG-200 showed lower activity and increased activation energy than glycogen-free glycogenin. Heat denaturation of glycogen-free and glycogen-bound glycogenin occurred at 51 and 64 degrees C, respectively. Active glycogenin was recovered after the glycogen-bound form was heated at 60-70 degrees C and immediately cooled. Treatment at 60 degrees C of the glycogen-free enzyme resulted in inactivation. This is the first report describing the inactivation and thermal stabilization of an enzyme by linked polysaccharide.
authors.affiliation: Centro de Investigaciones en Química Biológica de Córdoba, UNC-CONICET, Departmento de Química Biológica Dr. Ranwel Caputto, Facultad de Ciencias Químicas, Universidad Nacional de Córdoba, Ciudad Universitaria, 5000 Córdoba, Argentina.
authors.forename: J M
authors.initials: JM
authors.lastname: Romero
authors.forename: M E
authors.initials: ME
authors.lastname: Carrizo
authors.forename: G
authors.initials: G
authors.lastname: Montich
authors.forename: J A
authors.initials: JA
authors.lastname: Curtino
mesh_terms: D020106:Acrylamide / Q000737:chemistry; D000345:Affinity Labels; D000818:Animals; D001665:Binding Sites; D004355:Drug Stability; D005964:Glucosyltransferases; D006003:Glycogen / Q000737:chemistry / Q000378:metabolism / Q000494:pharmacology*; D006023:Glycoproteins / Q000037:antagonists & inhibitors* / Q000737:chemistry / Q000378:metabolism; D006031:Glycosylation; D006358:Hot Temperature; D066298:In Vitro Techniques; D007700:Kinetics; D011485:Protein Binding; D011489:Protein Denaturation; D011509:Proteoglycans / Q000737:chemistry / Q000378:metabolism; D011817:Rabbits; D014357:Trypsin / Q000737:chemistry; D014532:Uridine Diphosphate Glucose / Q000378:metabolism
chemical_list: D000345:Affinity Labels; D006023:Glycoproteins; D011509:Proteoglycans; C051887:glycogenin; D020106:Acrylamide; D006003:Glycogen; D005964:Glucosyltransferases; D014357:Trypsin; D014532:Uridine Diphosphate Glucose