Polysaccharides biological functions

About the same time, a new international research journal, Carbohydrate Research, appeared (volume 1) in 1964. It has become the principal journal for the publication of all aspects of carbohydrate research, such as chemical synthesis and modification enzymatic synthesis organic and enzymatic mechanisms involving carbohydrates carbohydrate metabolism conformational analysis isolation of carbohydrates from natural sources analytical methods chemistry of monosaccharides, oligosaccharides, and polysaccharides biological function of carbohydrates and physical properties. Approximately four to five volumes are published each year. 

In both their industrial and biological functions, the 3-dimensional characteristics of carbohydrates are important. Many of these stereochemical features are described for carbohydrates in the classic text by Stoddart (2). The inqportance of stereochemistry is underscored by the unique chemical and physical properties of the individual sugars, many of which are configurational isomers. Stereochemistry also plays a role in detentlining the properties of polysaccharides. Molecular shape is as significant for the properties of an industrially modified starch as it is for the recognition of one particular blood type and the rejection of others. 

A. O. Tzianabos (2000). Polysaccharide immunomodulators as therapeutic agents structural aspects and biologic function. Clin. Microbiol. Rev. 13 523-533. 

N 145 "Polysaccharide Conformation. Part VI. Computer Model-Building for Linear and Branched Pyranoglycans. Correlations with Biological Function. Preliminary Assessment... 

For conformational transitions to occur in polysaccharide solutions and for the biological associations of polysaccharides to be readily and conveniently temperature-reversible226 is unusual. Hence, it is fortunate that systems have been discovered in which both of these types of behavior are modelled and can be observed together. It is to be expected that such systems will prove useful in the further development of the theory of conformation in respect of biological function. 

Structural elucidation of natural macromolecules is an important step in understanding the relationships between the chemical properties of a biomolecule and its biological function. The techniques used in organic structure determination (NMR, IR, UV, and MS) are quite useful when applied to biomolecules, but the unique nature of natural molecules also requires the application of specialized chemical techniques. Proteins, polysaccharides, and nucleic acids are polymeric materials, each composed of hundreds or sometimes thousands of monomeric units (amino acids, monosaccharides, and nucleotides, respectively). But there is only a limited number of these types of units from which the biomolecules are synthesized. For example, only 20 different amino acids are found in proteins but these different amino acids may appear several times in the same protein molecule. Therefore, the structure of... 

Carbohydrates are characterized by the presence of polyhydroxylic aldehyde or poly-hydroxylic ketone structures or polymers of such units. Sugars and polysaccharides have definite three-dimensional structures that are important for many biological functions. They are hydrophilic and thus easily accessible to aqueous reaction mediums. The chemistry of bioconjugation using carbohydrate molecules begins with an understanding of the building blocks of polysaccharide molecules. 

Proteins, nudeic adds, and polysaccharides all serve critical biological functions. They are synthesized for specific purposes and are essential to the lives of the organisms in which they occur. The role of the polyisoprenes, on the other hand, is less obvious and less well understood. Because their backbones contain a large number of double bonds, they decompose readily when exposed to sunlight or to oxygen in the air. Therefore, rubber did not become a widely useful material until the invention of vulcanization in the 1850s by Charles Goodyear and Thomas Hancock (see Chapter 4). 

Biological Functions of Oligosaccharides and Polysaccharides. Polysaccharides serve two important biological roles. Glycogen and starch are polymers of glucose units linked in a(l —> 4) linkages that serve as carbohydrate reserves for animals, bacteria, and plants. Because these polymers are readily converted to intermediates for pathways that yield metabolic energy, they can also be... 

Sect. 2 below summarizes some of the important structures containing pyruvic acid acetals. The structural diversity, methods for structure elucidation, biosynthesis and biological function of these oligo- and polysaccharides will be briefly discussed. Sect. 3 gives an overview of the synthetic methods for the stereoselective preparation of pyruvated building blocks for oligosaccharide synthesis. Here, special attention is paid to pyruvated glycosyl donors, and their application to the synthesis of selected structures is presented in Sect. 4. 

E. Rees and W.E. Scott, Polysaccharide conformation. Part VI. Computer model building for linear and branched pyranoglycans. Correlation with biological function. Preliminary asesssment of interresidue forces in aqueous solution. J.Chem. Soc. B. (1971) 469. 

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