Homoglycans linear

Homoglycans, linear Glucans cellulose, amylose, chitin, laminaran, lichenan, crown gall polysaccharide, pustulan... 

Cellulose, a linear homoglycan of pi 4-linked glucose residues, is the most abundant organic substance in nature. Almost half of the total biomass consists of cellulose. Some 40-50% of plant cell walls are formed by cellulose. The proportion of cellulose in cotton fibers, an important raw material, is 98%. Cellulose molecules can contain more than 10" glucose residues (mass 1-2 10 Da) and can reach lengths of 6-8 pm. 

Chitin is the only known example of a homoglycan containing glucosamine, being a linear polymer of acetyl-D-glucosamine. Chitin is of widespread occurrence in lower... 

In no known instance do polysaccharides occur as a cage or three-dimensional net structure. They are either linear, cyclic, or branched. It is apparent that when a branch point is introduced the glycosidic bond connects different positions from those connected in the linear portions between branches. It is common to find the same kind of glycosidic linkage at all branch points in a homoglycan. If more than one type of sugar unit... 

Even in a linear homoglycan it is possible for more than one type of glycosidic linkage to be prevalent. In such a molecule the linkages do not occur randomly but are usually in an ordered arrangement. 

The solubility of polysaccharides and other functional properties depend on their structure. Linear polysaccharides dissolve with difficulty or they are completely insoluble. Such polymers are usually homoglycans with strong intra- and intermolecular non-bonding interactions. As a result of highly organised structures, some parts of the molecules even have crystalline structure and polar groups capable of interaction with water are not available. An example of a polysaccharide insoluble in cold water and soluble in hot water is amylose. Cellulose is insoluble even in hot water, but it is soluble in alkaline solvents. 

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