Carbohydrates are much, much more than simple biochemical fuel or - as polymers - the molecular concrete to convey stability to insects and plants. As obvious sign for a broad physiological role, sugar chains are also frequently presented by proteins and lipids. This part of cellular glycoconjugates affords a versatile means to build biochemical signals.
In fact, oligosaccharides have an exceptional talent in this respect. They surpass any other class of biomolecule in coding capacity within an oligomer (code word). Four structural factors account for this property: the potential for variability of linkage points, anomeric position and ring size as well as the aptitude for branching (first and second dimensions of the sugar code). Specific intermolecular recognition is favoured by abundant potential for hydrogen/coordination bonds and for C-H/pi-interactions.
Fittingly, an array of protein folds has developed in evolution with abilty to select certain glycans from the natural diversity. The thermodynamics of this reaction profits by the occurence of these ligands in few, energetically favoured conformers, comparing favourably to highly flexible peptides (third dimension of the sugar code). Sequence, shape and local aspects of glycan presentation (e.g. multivalency) are key factors to regulate the avidity of lectin binding.
On the level of cells, distinct glycan determinants, a result of enzymatic synthesis and dynamic remodelling, are being defined as biomarkers. Their presence gains a functional perspective by co-regulation of the cognate lectin as effector for e.g. growth regulation. The orchestration of glycan and lectin expression is an efficient means with far-reaching relevance to exploit the coding potential of oligosaccharides physiologically and medically.
To contribute to understand sugar coding on the levels of
- glycan structure
- glycan-lectin interaction, with implications for drug design
- regulation of expression of glycan determinants and cognate lectins, with biomedical relevance
To accomlish this goal a network of close collaborations with colleagues and friends in Europa, Asia, America and Australia is essential to which we welcome newcomers any time.