engleski

Sweet secret of the multicellular life

Carbohydrates have been in the center of human interest since the very beginning of civilization, but we have only recently started to understand the importance of complex oligosaccharides (glycans) attached to protein or lipid backbones. This is perhaps not surprising, since the branched structures of sugars makes analysis of glycoconjugates significantly more challenging than the analysis of linear DNA and protein sequences. A typical glycan is a complex molecule containing between 10 and 15 monosaccharides linked in a rather complicated manner that many of us have not yet learned to interpret. Two or more such glycans are attached to the protein backbone of an average glycoprotein, and since there is no genetic blueprint for glycans, individual glycan structures can vary depending on the current level of expression and intracellular localization of biosynthetic enzymes (glycosyltransferases and glycosidases). Consequently, slightly different glycan structures can be attached to the same protein backbone, and after the glycosylation of a protein is completed, proteins with the same amino acid sequence can end up in one of several hundred possible glycoforms. Since naturally glycosylated proteins still cannot be produced in vitro, structural analysis has to be performed on small quantities of glycoproteins that can be isolated from nature, and considering the complexity of glycosylation, this can be a formidable task.

glycosylation; lectins; glycoproteins; evolution

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