Towards defining the role of glycans as hardware in information storage and transfer: Basic principles, experimental approaches and recent progress

The term 'code' in biological information transfer appears to be tightly an d hitherto exclusively connected with the genetic code based on nucleotides and translated into functional activities via proteins. However, the recen t appreciation of the enormous coding capacity of oligosaccharide chains of natural glycoconjugates has spurred to give heed to a new concept: versati le glycan assembly by the genetically encoded glycosyltransferases endows c ells with a probably not yet fully catalogued array of meaningful messages. Enciphered by sugar receptors such as endogenous lectins the information o f code words established by a series of covalently linked monosaccharides a s fetters for example guides correct intra- and intercellular routing of gl ycoproteins, modulates cell proliferation or migration and mediates cell ad hesion. Evidently, the elucidation of the structural frameworks and the rec ognition strategies within the operation of the sugar code poses a fascinat ing conundrum. The far-reaching impact of this recognition mode on the leve l of cells, tissues and organs has fueled vigorous investigations to probe the subtleties of protein-carbohydrate interactions. This review presents i nformation on the necessarily concerted approach using X-ray crystallograph y, molecular modeling, nuclear magnetic resonance spectroscopy, thermodynam ic analysis and engineered ligands and receptors. This part of the treatise is flanked by exemplarily chosen insights made possible by these technique s. Copyright (C) 2001 S. Karger AG, Basel.