Cell surface oligosaccharides

The important role saccharides play in biology, especially in recognition processes, led researchers to work on the development of multivalent so-called neo-glycoconjugates the numerous biological roles of cell surface oligosaccharides... 

Constitution of cell surface oligosaccharides or polysaccharides includes the following ... 

There are many glycosylation mutants of cultured mammalian cells and yeast. They have been selected as rare survivors of treatments that kill cells expressing a particular carbohydrate or glycoprotein at the cell surface. For example, plants produce a variety of proteins, called lectins, which bind to cell surface oligosaccharides. Lectins are toxic to mammalian cells. They can be used to select for mutants that no longer bind the lectin because they lack a particular carbohydrate at the cell surface. Such glycosylation mutants have low amounts of glycoproteins that require carbohydrates for stable expression. 

K. Sasaki, Y. Nishida, T. Tsurumi, H. Uzawa, H. Kondo, and K. Kobayashi, Facile assembly of cell surface oligosaccharide mimics by copolymerization of carbohydrate modules, Angew. Chem. Int. Ed, 41 (2002) 4463 1467. 

Located at the terminus of numerous cell-surface oligosaccharides, sialic acids are ideally positioned to participate in biological processes including cell-biomolecule-mediated recognition phenomena, acting as receptors for viruses and bacteria, cellcell communication, and as markers in certain diseases [9, 27, 29],... 

The high affinity of Con A for cell surface oligosaccharides has also facilitated the immobilization of various cells including those of yeast [131], red blood cells [126, 128] and Trichosporon cutaneum [132]. An early study has also described the co-immobilization of enzymes and living cells using Con A [133]. More recently Habibi-Rezaei and Nemat-Gorgani [134] immobilized submitochondrial particles prepared from beef liver mitochondria on Con A support for continuous catalytic transformations involving succinate-cytochrome c reductase. 

L-Fucose occurs either at terminal or preterminal positions of many cell surface oligosaccharide ligands. These fucosylated oligosaccharides mediate cell-cell recognition and adhesion-signaling pathways. Some of these processes... 

We begin with an overview of the structures of glycoconjugates on cell surfaces (for more comprehensive reviews, see Refs. 2, 12-14, and 24). Next, the pathways of monosaccharide interconversions inside the cell are smnmarized, providing a framework for opportunities in unnatural monosaccharide metabolism. Specihc examples of modihed sugars and their effects on cells are then presented. Finally, the biosynthetic pathway of sialic acid is discussed with respect to its utility for cell surface oligosaccharide engineering. 

Figure 2 Metabolic substrate engineering as a strategy for modulating cell surface oligosaccharide structure. Modified metabolic substrates can intercept a biosynthetic pathway in two ways the pathway might be inhibited, leading to truncated structures on the cell surface, or the modified substrate might be incorporated into oligosaccharides in place of the normal substrate.

Chen L, Zhang W, Fregien N, Pierce M (1998) The her-2/neu oncogene stimulates the transcription of V-acetylglucosaminyltransferase V and expression of its cell surface oligosaccharide products. Oncogene 17 2087-2093... 

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