Polysaccharide systems, structuring cellulose

Muhlethaler K (1969) Fine structure of natural polysaccharide systems. In Marchessault RH (ed), Proceedings of 6th cellulose conference. Wiley, New York, 57-67 Murphy RJ, Barnes HM and Dickinson DJ (2002) Vapor boron technology. In Enhancing the durability of lumber and engineered wood products. Forest Prodncts Society, Madison, Wisconsin, 251-6... 

Plants and animals synthesize a number of polymers (e.g., polysaccharides, proteins, nucleic acids) by reactions that almost always require a catalyst. The catalysts present in living systems are usually proteins and are called enzymes. Reactions catalyzed by enzymes are called enzymatic reactions, polymerizations catalyzed by enzymes are enzymatic polymerizations. Humans benefit from naturally occurring polymers in many ways. Our plant and animal foodstuffs consist of these polymers as well as nonpolymeric materials (e.g., sugar, vitamins, minerals). We use the polysaccharide cellulose (wood) to build homes and other structures and to produce paper. 

Brown, R. M., Herth, W., Franke, W. W., Romanovicz, D. The role of the Golgi apparatus in the biosynthesis and secretion of a cellulosic glycoprotein in Pleurochrysis a model system for the synthesis of structural polysaccharides. In Biogenesis of plant cell wall polysaccharides, pp. 207. Loewus, F. (ed.). New York Academic Press 1973... 

This subject has been of continuing interest for several reasons. First, the present concepts of the chemical constitution of such important biopolymers as cellulose, amylose, and chitin can be confirmed by their adequate chemical synthesis. Second, synthetic polysaccharides of defined structure can be used to study the action pattern of enzymes, the induction and reaction of antibodies, and the effect of structure on biological activity in the interaction of proteins, nucleic acids, and lipides with polyhydroxylic macromolecules. Third, it is anticipated that synthetic polysaccharides of known structure and molecular size will provide ideal systems for the correlation of chemical and physical properties with chemical constitution and macromolecular conformation. Finally, synthetic polysaccharides and their derivatives should furnish a large variety of potentially useful materials whose properties can be widely varied these substances may find new applications in biology, medicine, and industry. 

Polysaccharides and generally carbohydrates represent the main carbon sink in the plant cell. Polysaccharides commonly serve nutritional (e.g., starch) and structural (e.g., cellulose) functions in plants. Some polysaccharides are cytotoxic against certain types of cancer, such as mouse skin cancer, or tumor lines in vitro (e.g., mouse Sarcoma-180). However, most polysaccharides exert their action through stimulation of the immune system (cancer immunotherapy). Plants containing polysaccharides with anticancer properties include the following ... 

In a subsequent study, Da Silva et al. investigated the photo degradation of 4-chlorophenol on the polysaccharide cellulose and on silica [41]. In both systems, transient spectra and products were consistent with the assumption of heterolytic dehalogenation to give 4-oxocyclohexa-2,5-dienylidene. In cellulose, unsubstituted phenoxyl radicals and phenol were the main products, indicating that the polymer serves as H-donor for the carbene. There was no effect of O2 on the reaction course, which was explained by the protective effect of the macromolecular structure. In silica, which contained... 

The biosynthesis of most crystalline polymers is not well understood. The mechanism by which structural and insoluble proteins are assembled from monomers into structures such as cell membranes is almost completely unknown (33). A notable exception is the biosynthesis of polysaccharides which is believed to take place by phosphate displacement reactions of an activated subunit with the help of an enzyme system (33). The polymerization of bacterial cellulose is perhaps studied in most detail. Here the research has been helped because the reaction of monomer to crystalline polymer occurs extracellularly, remote from the bacterial surface (34). 

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