Glycomics

Elucidation of the genomes of different eukaryotes in the last millennium has taught us that the increasing complexity of higher organisms is largely unrelated to the total number of genes.
As a result the scientific community has shifted towards understanding the proteome, which contains a large multiplication of the genome by processes such as alternative splicing, protein processing and posttranslational modifications. It is estimated that the human proteome contains up to 1 million proteins compared to the 25,000 genes in the genome of man; however, this calculation suffers from ignoring the impact differential posttranslational modifications impart, which add orders of magnitudes to these numbers.

Glycosylation is one of the most abundant forms of posttranslational modifications of proteins, and carbohydrate science is inherently connected to protein science. While enormous efforts are now placed on proteomics, the next omics will undoubtedly be the field of glycomics. Although this is clear to most glycobiologists, the functional role of glycosylation is often underestimated in the protein science field.

Glycosylation is one of the most complex regulated processes of the cell, with more than 1,000 genes or more than 2% of the genome involving enzymes required for biosynthesis and metabolism of complex glycans. Complex carbohydrates play a wide array of different biological roles from direct effects on folding, processing, sorting, and functions of proteins, to serving as ligands in important adhesion events for cell-cell interactions. Deficiencies in glycosidases and glycosyltransferases lead to a large number of diseases, and our appreciation of subtle effects of defects in glycosylation is rapidly increasing. Complex carbohydrates play a major role for infectious diseases where they on one hand serve as the major ligands for microbial adhesions and hence provide the first contact with pathogens, and on the other hand serve in clearance mechanisms as well as major targets for host immunity. Finally, complex carbohydrates play an increasingly important role for biotechnology, which currently primarily involves formulation of therapeutics to enhance bioavailability of protein drugs and modulation of effecter functions of antibody drugs.