Inactivation and thermal stabilization of glycogenin by linked glycogen.

Autor: Romero JM; 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., Carrizo ME, Montich G, Curtino JA
Jazyk: angličtina
Zdroj: Biochemical and biophysical research communications [Biochem Biophys Res Commun] 2001 Nov 23; Vol. 289 (1), pp. 69-74.
DOI: 10.1006/bbrc.2001.5949
Abstrakt: 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.
(Copyright 2001 Academic Press.)
Databáze: MEDLINE
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