Glycobiology

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Defined in the broadest sense, glycobiology is the study of the structure, biosynthesis, and biology of saccharides (sugar chains or glycans) that are widely distributed in nature.[1] [2]Sugars or saccharides are essential components of all living things and aspects of the various different roles they play in biology are researched in various different medical, biochemical and biotechnological fields.

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[edit] History

The specific term glycobiology was coined in 1988 to recognize the coming together of the traditional disciplines of carbohydrate chemistry and biochemistry.[3] This coming together was as a result of a much greater understanding of the cellular and molecular biology of glycans. However as early as the late nineteenth century pioneering efforts were being made by Emil Fisher to establish the structure of some basic sugar molecules.

[edit] Glycoconjugates

Sugars may be linked to other types of biological molecule to form glycoconjugates. Glycoproteins, proteoglycans and glycolipids are the most abundant glycoconjugates found in mammalian cells. They are found predominantly on the outer cell wall and in secreted fluids. Glycoconjugates have been shown to be important in cell-cell interactions due to the presence on the cell surface of various glycan binding receptors in addition to the glycoconjugates themselves.[4][5]

[edit] Glycomics

Main article: Glycomics

"Glycomics, analogous to genomics and proteomics, is the systematic study of all glycan structures of a given cell type or organism" and is a subset of glycobiology.[6]

[edit] Difficulties in the study of sugar structures

Part of the variability seen in saccharide structures is because monosaccharide units may be coupled to each other in many different ways, as opposed to the amino acids of proteins or the nucleotides in DNA, which are always coupled together in a standard fashion.[7] The study of saccharide structures is also complicated by the lack of a direct template for their biosynthesis, contrary to the case with proteins where their amino acid sequence is determined by their corresponding gene.

Saccharides are also secondary gene products and as such are generated by the coordinated action of many enzymes in the subcellular compartments of a cell. Thus, the structure of a saccharide may depend on the expression, activity and accessibility of the different biosynthetic enzymes. This means it is not possible to use recombinant DNA technology in order to produce large quantities of saccharides for structural and functional studies as has been used extensively for protein studies.

[edit] Modern Tools and Techniques for Glycan Structure Prediction

Accurate machines and advanced software programs when used in combination can unlock the mystery of glycan structures elucidation. One such technique is Mass Spectrometry which uses three principle units which are the ionizer, analyzer and detector . Fast Atom Bombardment (FAB) mass spectrometers is a powerful tool for characterizing the complex carbohydrates. this technique can be coupled with sensitive array detector technology.

[edit] Software for MS Data Interpretation

Mass Spectrometry data needs visualization since glycan structures and their 3 D configuration. Some free and commercial software products make this task easy for glycobiologists. Here are some of them: 1. GlycoWorkbench - This software matches fragments to experimental peaks list. It also has a visual editor for building glycan structures [8].
2. OSCAR - De novo analysis of permethylated glycans. Accepts one or more disassembly pathways and produces structures consistent with them.

[edit] References

  1. ^ Varki A, Cummings R, Esko J, Freeze H, Stanley P, Bertozzi C, Hart G, Etzler M (2008). Essentials of glycobiology. Cold Spring Harbor Laboratory Press; 2nd edition. ISBN 0-87969-770-9. http://www.ncbi.nlm.nih.gov/bookshelf/br.fcgi?book=glyco2. 
  2. ^ Varki A, Cummings R, Esko J, Freeze H, Hart G, Marth J (1999). Essentials of glycobiology. Cold Spring Harbor Laboratory Press. ISBN 0-87969-560-9. http://www.ncbi.nlm.nih.gov/books/bv.fcgi?rid=glyco.TOC&depth=2. 
  3. ^ Rademacher TW, Parekh RB and Dwek RA. (1988). "Glycobiology". Annu. Rev. Biochem. 57: 785–838. doi:10.1146/annurev.bi.57.070188.004033. PMID 3052290. 
  4. ^ Ma BY, Mikolajczak SA, Yoshida T, Yoshida R, Kelvin DJ, Ochi A (2004). "CD28 T cell costimulatory receptor function is negatively regulated by N-linked carbohydrates". Biochem. Biophys. Res. Commun. 317 (1): 60–7. doi:10.1016/j.bbrc.2004.03.012. PMID 15047148. 
  5. ^ Takahashi M, Tsuda T, Ikeda Y, Honke K, Taniguchi N (2004). "Role of N-glycans in growth factor signaling". Glycoconj. J. 20 (3): 207–12. doi:10.1023/B:GLYC.0000024252.63695.5c. PMID 15090734. 
  6. ^ Cold Spring Harbor Laboratory Press Essentials of Glycobiology, Second Edition
  7. ^ Kreuger, J (2001). Decoding heparan sulfate. http://www.diva-portal.org/demo/theses/abstract.xsql?dbid=1499. Retrieved on 2008-01-11. 
  8. ^ http://en.wikipedia.org/w/index.php?title=Glycobiology&action=edit

[edit] External links

  • The Functional Glycomics Gateway. This monthly updated webresource about all aspects of carbohydrate function in biology is a collaboration of Nature and the Consortium for Functional Glycomics.
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