Glycochemistry: Overview and progress

This chapter provides an overview of the evolution of glycan chemistry from the time of Emil Fischer to the burgeoning field of glycomics. The International Union of Pure and Applied Chemistry (IUPAC) defines glycan as 'synonymous with polysaccharides', meaning compounds consisting of a large number of monosaccharides linked to each other through glycosidic bonds. The term 'glycan' is used to describe the carbohydrate portion of glycoconjugates such as glycoproteins and glycolipids. While carbohydrate chemistry has enjoyed remarkable progress, the search for alternative glycosylation strategies for the synthesis of biologically important compounds is an ongoing endeavor. The efforts of chemists and biologists combined with recent advances in spectroscopic techniques will yield answers to many of the questions surrounding the structure and function of glycans and the microdomains in which they reside. The structural complexity and numerous isoforms found in naturally occurring glycans pose significant challenges in isolating pure and homogeneous samples of glycolipids, glycoconjugates, and glycoproteins.