Nature of α and β Particles in Glycogen Using Molecular Size Distributions

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• 作者：Mitchell A. Sullivan ; Francisco Vilaplana ; Richard A. Cave ; David Stapleton ; Angus A. Gray-Weale ; Robert G. Gilbert
• 刊名：Biomacromolecules
• 出版年：2010
• 出版时间：April 12, 2010
• 年：2010
• 卷：11
• 期：4
• 页码：1094-1100
• 全文大小：277K
• 年卷期：v.11,no.4(April 12, 2010)
• ISSN：1526-4602

文摘

Glycogen is a randomly hyperbranched glucose polymer. Complex branched polymers have two structural levels: individual branches and the way these branches are linked. Liver glycogen has a third level: supramolecular clusters of β particles which form larger clusters of α particles. Size distributions of native glycogen were characterized using size exclusion chromatography (SEC) to find the number and weight distributions and the size dependences of the number- and weight-average masses. These were fitted to two distinct randomly joined reference structures, constructed by random attachment of individual branches and as random aggregates of β particles. The z-average size of the α particles in dimethylsulfoxide does not change significantly with high concentrations of LiBr, a solvent system that would disrupt hydrogen bonding. These data reveal that the β particles are covalently bonded to form α particles through a hitherto unsuspected enzyme process, operative in the liver on particles above a certain size range.