Solution Properties of Glycogen. 1. Dilute Solutions

Abstract

Dilute solutions of glycogen from mussels (shellfish) and of different degradation steps were investigated by static and dynamic light scattering, viscometry, and end group analysis of the reducing end. The data were analyzed in comparison with theory for hyperbranched polymers. In the monomer of the A type, the functional group B2 (resulting in α(1, 6) linkages) has a much lower reactivity than that of the B1 group (leading to α(1, 4) linkages and chain growth). Qualitative agreement in behavior was found with the nonfractionated samples, but the effective branching density, derived from the applied physical techniques, was found to be considerably lower than that known from chemical analysis. SEC fractionation in on-line combination with multiple-angle laser light scattering and a viscosity detector revealed molar mass distributions that are composed of two main components. These components differ in their physical properties. The required examination was possible because R g and [η] could be measured for each slice. Shrinking factors g = R g 2 b/R g 2 lin and g‘ = [η]b/[η]lin were determined. The results of quantitative analysis are discussed in relation to current theories.

Molar mass and solution conformation of branched α(1→4), α(1→6) Glucans. Part I: Glycogens in water

“…The values for intrinsic viscosity (Table 1) are consistent with those found previously (Ioan et al, 1999;Geddes, Harvey & Wills, 1977a) and show no molar mass dependency (Figure 3(c) and Table 2), which is typical for spherical macromolecules in solution (Tombs & Harding, 1998).…”

“…3) which is close to the theoretical value for a hard sphere (Ioan et al, 1999) of 3.0 (see Table 3). …”

“…The weight average molar mass and the z-average radius of gyration for mussel glycogen (4.6 x 10 6 g/mol and 13.7 nm) are lower than was previously estimated (Ioan et al, 1999) 6.2 x 10 6 g/mol and 26 nm, although taking into account the intrinsic viscosity of this glycogen ([η] = 6.67 ml/g) from the same paper the r g , z can be estimated to be 14.6 nm based on the following approximation for spheres (Grubisic, Rempp & Benoit, 1996):…”

The Molecular Size Distribution of Glycogen and its Relevance to Diabetes

“…While size-exclusion chromatography, SEC (also known as GPC), has been used to characterise the structure of polymers since the 1960s, it has only recently been applied to glycogen. [4,[8][9][10][11][12] Before the use of this technique, the macromolecular structure of glycogen was generally characterised using TEM [3,13,14] (where size histograms have often been employed) and by sucrose density centrifugation. [15][16][17] While useful in gaining insight into the nature of glycogen a-and b-particles, there are several limitations as to what can be concluded using these techniques.…”

“…There have however been several encouraging studies using aqueous SEC to characterise synthetic and commercial glycogen. [9,11,34,35] There are several other advantages to using an aqueous system: water is cheaper, safer, easier to dispose of and more physiologically relevant than DMSO. The universal calibration assumption was used here.…”