Polysaccharides structures and functions

J.F. Thibauit, M. Rinaudo, Proc. Int. workshop on "Plant Polysaccharides, Structure and Function" Nantes, France (1984) 214. 

Figure 4.21 An illustration of how the configuration of glycosidic bonds determine polysaccharide structure and function. The P-1-4 linkages in cellulose favourize straight chains, optimal for structural purposes, whereas the a-1-4 linkages are favourable to bent structures, better adapted to storage in a hydrated form.

Chitin is a polysaccharide structurally and functionally related to cellulose. The structure is derived from that of cellulose by replacing one of the hydroxyl groups on each monosaccharide unit by an acetamido group, —NHCOCH3. Chitin is the structural polysaccharide of lower plants, such as fungi, and of invertebrates, particularly arthropods. It is the second most abundant organic substance on Earth. 

Richards, G. N. Proc. Inti. Workshop on Plant Polysaccharides, Structure and Function Nantes, France, 9-11 July 1984, p.47-53. 

Enzymes DegradingMacromolecules. Enzymes that degrade macromolecules such as membrane polysaccharides, structural and functional proteins, or nucleic acids, have all shown oncolytic activity. Treatment strategies include the treatment of inoperable tumors with pepsin (1) antitumor activity of carboxypeptidase (44) cytotoxicity of ribonudease (45—47) oncolytic activity of neuraminidase (48—52) therapy with neuraminidase of patients with acute myeloid leukemia (53) antitumor activity of proteases (54) and hyaluronidase treatment in the management of human solid tumors (55). 

In most cases, the precise functions of polysaccharides are not known even their primary sequences are very hard to determine using current analytical techniques. Thus, a major challenge is to crack the carbohydrate code and determine the structures and functions of all the polysaccharides found on human cells. Terms such as glycomics have already been coined to describe such global efforts. 

Christensen, B. E. (1999). Physical and chemical properties of extracellular polysaccharides associated with biofilms and related systems. In Microbial Extracellular Polymeric Substances. Characterization, Structure and Function, eds. Wingender, J., Neu, T. R. and Flemming, H.-C., Springer-Verlag, Berlin, pp. 143-154. 

O Neill, M. A., Ishii, T., Albersheim, P, Darvill, A. G. (2004). Rhamnogalacturonan II structure and function of a borate cross-linked cell wall pectic polysaccharide. Ann. Rev. Plant Biol, 55,109-139. 

The chapters of Part I are devoted to the structure and function of the major classes of cellular constituents water (Chapter 2), amino acids and proteins (Chapters 3 through 6), sugars and polysaccharides (Chapter 7), nucleotides and nucleic acids (Chapter 8), fatty acids and lipids (Chapter 10), and, finally, membranes and membrane signaling proteins (Chapters 11 and 12). We supplement this discourse on molecules with information about the technologies used to study them. Some of the techniques sections are woven throughout the molecular descriptions, although one entire chapter (Chapter 9) is devoted to an integrated... 

The glass transition processes in foods may result from a rapid removal of water from solids. Based on that, e.g., the Tg values of anhydrous polysaccharides are high, and the food materials may decompose at temperatures below Tg (Kokini et al 1994 Roos and Karel, 1991b). The glass temperature transition affects viscosity, stickiness, crispness, collapse, crystallization, and ice formation, and can strongly influence deteriorative reaction rates. This provides a new theoretical and experimental framework for the study of food systems to unify structural and functional aspects of foods, described in terms of water dynamics and glass dynamics. 

---