Homopolysaccharides, biosynthesis

Other examples of exocellular homopolysaccharides whose biosynthetic process has been investigated include D-mannuronan,204,205 an intermediate in the biosynthesis of bacterial alginic acid (mentioned in Section III,l,c), and bacterial cellulose. 

The biosynthesis of poly-2 -> 8 or -2 9-(A-acetyl-D-neuraminic acid) capsular polysaccharide (colominic acid) from E. coli or N. meningitidis (see Chapter 6, Fig. 6.20 for the structures) has also been shown to involve a polyprenol phos-phoryl A-acetyl-D-neuraminic acid lipid intermediate formed from CMP-NeuNAc [67,68]. This is an example of the biosynthesis of a homopolysaccharide that requires a polyprenol phosphate coenzyme lipid carrier. 

Molecules with a long main chain (backbone) and a few short side chains are called linearly branched p. The majority of all p. are formed by biosynthesis in green plants or in fungi and bacteria. Some important p. are synthesized by animals, such as - chitin, hyaluronic acids or glycogen. P. can be hydrolized (->hydrolysis). P. that yield only one monomer are called homopolysaccharides if there are two or more different monomers, they are heteropolysaccharides. 

---