Study On The Molecular Conformation And Chemical Modified Derivatives Of Curdlan

Polysaccharide is a group of biopolymers that widely distributed in animal, plant and microorganism, and it plays essential roles in living organisms. Curdlan is a bacterial polysaccharide formed by fermentation, and its linear structure is composed entirely of (1→3)-β-D glucosidic linkages. Curdlan has unique gelling properties of forming either low-set gels or high-set gels depending on the heating temperature. It has utility as a food additive in its ability to form an elastic gel and shows strong bioactivities, such as anti-tumor and anti-HIV activities, which attracted more and more attention of the food industry, medicine and healthcare field.The characteristic of neutrality, non-branched chains, non-complicated substituent, simple repeat unit and gelling by heating alone make curdlan a model to understand the mechanism of gel formation. The main contents and conclusions in this work are listed as follows:We focused firstly on the curdlan-DMSO system. Five samples of curdlan ranging in molecular weight from 5.1×104 to 192×104 were used to determine their conformational parameters and molecular dimensions in dimethyl sulfoxide at 25 oC. Mark-Houwink equation was established as [η]=4? 8×10?4Mw0.65. On the basis of unperturbed wormlike chain models, the molecular parameters were estimated as follows: the molar mass per unit contour length ( M L) = 694 nm-1, persistence length (q ) = 5.81 nm, molecular diameter (d ) = 0.99 nm, and characteristic ratio ( C∞) =...