[CARAPAX - Chitosan Activates Resistance Against Pathogens After eXposure]
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Chitosan Structure

Chitosan is a linear co-polymer of glucosamine (2-desoxy-2-amino--D-glucopyranose, glcN) and N-acetylglucosamine (2-desoxy-2-acetamido--D-glucopyranose, glcNAc) in -1,4-glycosidic linkages. It is chemically closely related to chitin, the fully N-acetylated -1,4-polymer of glcNAc, and to cellulose, the -1,4-polymer of glucose (-D-glucopyranose, glc). All of these polysaccharides form stretched molecules able to form more or less crystalline fibres by hydrogen-binding.

In contrast to cellulose (the fiber-forming component of plant cell walls) and chitin (the fiber-forming component of fungal cell walls), chitosans possess positive charges at physiological pH values due to their free amino groups. Chitosan, therefore, is one of the very rare natural polymers with a polycationic character which allows it to interact with the many polyanionic polymers such as proteins, DNA, and membranes. This physico-chemical interaction most likely is a prerequisite for the diverse biological activities of chitosans.

The physico-chemical properties of chitosans largely depend on their degree of polymerisation (DP) and their degree of N-acetylation (DA). Consequently, also the biological properties of chitosans are influenced by these parameters. In addition, however, the bio-activities may not only depend on the number of acetyl groups, but also on their distribution along the linear polysaccharide chain.

The CARAPAX project is part of the Fifth Framework Research Program of the European Union, Key action 5
"Sustainable Agriculture, Fisheries and Forestry" of the "Quality of Life and Management of Living Resources" Program.
© M. Hellweg - S. Lenhert 2002-05

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