Читать книгу Polysaccharides - Группа авторов - Страница 43

It is matrix polysaccharides of the algal cell wall, especially in the cell wall of brown algae. Alginate have a linear structure and made of (1–4)-linked β-D-mannuronic acid subunits with epimerically attached α-L-guluronic acid at C-5 position. During biosynthesis of algal cell wall alginates synthesized as the polymeric chains of homomannuronan. Later on, the β-D-mannuronic acid subunits are partly change into α-L-guluronic acid units through C-5 epimerase enzyme (Figure 2.2A). So, these homopolymeric chains form helical structures which stabilized through intramolecular forces such as, hydrogen bonding, etc. [32].

The ratio between mannuronic acid and guluronic acid in algal cell wall alginates depends upon the sources and geographical distribution of algal raw materials, seasonal collection, anatomical part of the algal thalli and the method of its extraction. Algal cell wall alginate could be classified on the basis of high and low mannuronic acid contents, high guluronic acid contents or their intermediates. It also reported that the tissue of young algal thalli have high content of mannuronic acid that compared to different tissue of older thalli of the algae [32, 35].