Polymerization polysaccharide chain growth

The block mechanism of chain assembly is characteristic for polymeric chains of the UGT type (see Salmonella O-specific polysaccharides 10-12 and 18) and the UG type (see capsular polysaccharides 25, 27, and 33), with UDP-activated sugars serving as initiators of chain growth. It seems rather safe to suggest that the biosynthesis of other polymers of these types occurs through a block mechanism as well. 

The third component in the Wzy/Wzx-dependent pathway is the Wzz protein. Wzz generates the strain-specific chain length distribution of 0 polysaccharide chain lengths as reflected in characteristic clusters of bands following gel electrophoresis of LPS samples.The function of the Wzz protein is not required for bacterial growth in the laboratory setting, as polymerization can proceed in the absence of this protein. However, the distribution of the 0 polysaccharide chain length is critical for virulence. 

Biopolymers are polymers formed in nature during the growth cycles of all organisms hence, they are also referred to as natural polymers. The biopolymers of interest in this review are those that serve in nature as either structural or reserve cellular materials. Their syntheses always involve enzyme-catalyzed, chain-growth polymerization reactions of activated monomers, which are generally formed within the cells by complex metabolic processes. The most prevalent structural and reserve biopolymers are the polysaccharides, of which many different types exist, but several other more limited types of polymers exist in nature which serve these roles and are of particular interest for materials applications. The latter include the polyesters and proteins produced by bacteria and the hydrocarbon elastomers produced by plants (e.g. natural rubber). In almost all cases (natural rubber is an exception), all of the repeating units of these biopolymers contain one or more chiral centers and the repeating units are always present in optically pure form that is, biopolymers with asymmetric centers are always 100% isotactic. 

Microbial polysaccharides constitute a specific class of biopolymers. These biopolymers are formed during the growth of the living organisms, and are thus, called natural polymers. Their synthesis usually involves enzymatic catalysis and an increase in the chain through polymerization reactions of the monomers, typically inside the cells, mediated by complete metabolic processes (3,4). 

The actual process of growth involves the building up of substances such as proteins, polysaccharides, and nucleic acids, aU of which are macromolecular compounds formed by reactions of polymerization and polycondensation. Reactions of this type are not unfamiliar in the inanimate world. They usually involve radical chains, and sometimes they are heterogeneous. In the formation of ethylene polymer... 

Polymerization reactions proceed either by the step growth or the chain addition mechanisms. Step-growth polymerizations require monomers with at least two functional groups and are involved in the manufacture of several industrially important polymers such as polyamides, polyesters, and in the formation of biopolymers such as polysaccharides, proteins and polypeptides in nature. 

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