Pii: S0268-005x(00)00007-2
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چکیده
Estimation of the influence of the degree of esterification on the hydrodynamic properties of citrus pectins provides a simple demonstration of how chemical variation can influence structural properties of polysaccharides. Five citrus pectins with average degree of esterification 77.8, 65.0, 53.9, 37.8 and 27.9%, respectively were studied using capillary viscometry, sedimentation velocity, sedimentation equilibrium and size exclusion chromatography coupled to multi-angle laser light scattering (SEC-MALLS). Molecular weights (weight average) for all five pectin samples were within the range 190 000 ^ 30 000 g/mol as confirmed by the independent techniques of sedimentation equilibrium and SEC-MALLS. Estimates for the conformation dependent Wales–van Holde ks=h and frictional f =f0 ratios from the hydrodynamic data clearly indicates increasing chain stiffness with decreasing degree of esterification. It appears that both steric and electrostatic interactions are important in these conformational changes. q 2000 Elsevier Science Ltd. All rights reserved.
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تاریخ انتشار 2000