Glycans diversity

Decoding Glycan Diversity Strategies for Sequencing Glycans... 

Bertozzi CR, Rabuka D (2009) Structural basis of glycan diversity. In Varki A, Cummings RD, Esko JD et al (eds) Essentials of glycobiology, 2nd edn. Cold Spring Harbor Laboratory Press, Cold Spring Harbor... 

Plant-based production systems are now being used commercially for the synthesis of foreign proteins [1-3]. Post-translational modification in plant cells is similar to that carried out by animal cells plant cells are also able to fold multimeric proteins correctly. The sites of glycosylation on plant-produced mammalian proteins are the same as on the native protein however, processing of N-linked glycans in the secretory pathway of plant cells results in a more diverse array of glycoforms than is produced in animal expression systems [4]. Glycoprotein activity is retained in plant-derived mammalian proteins. 

In spite of the apparent extreme diversity of the / -(l- 4) glycans— from crystalline cellulose to components of bacterial cell walls—the similarity of the environments around their / -(1— 4) glycosidic linkage raises the question of a common catalytic site structure in the various / -(l- 4) glycoside hydrolases. This chapter will review the evidence for and against a general lysozyme type mechanism. 

A diverse range of glycan forms may be produced in some recombinant proteins. For example, the HIV envelope glycoprotein (gpl20) produced from CHO cells contains 24 occupied sequons, of which 13 are complex glycans and 11 are high mannose or hybrid structural forms (Leonard etal., 1990). 

Due to the structural complexity of carbohydrates, preparation of structurally well-defined carbohydrates with broad diversity is a key issue for glycan array development. Because it is difficult to obtain sufficient quantities of glycans from natural sources, chemical or chemoenzymatic methods or even pure enzymatic methods have been used to address this deficiency. The recent advances in carbohydrate syntheses that are described in other chapters of this book have greatly reduced the labor for glycan preparation. 

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