Reaktionstechnische Untersuchungen zur enzymatischen Glycolisierung von Peptiden

Whereas twenty years ago, the amino acid sequence of a protein was considered most relevant for its biological activity, it is now obvious that intercellular recognition processes are often mediated by protein glycosylation sites. Important examples are inflammation, infections and tumor metastasis, respectively. For the purpose of biochemical research as well as for drug design, fragments of bioactive proteins are needed, which are very often only available by laborious multistep synthesis. $\textit{In vivo}$, Glycosylation is catalysed by glycosyltransferases. These enzymes selectively transfer activated sugars with quantitataive yields. Enzymatic glycolylation in $\textit{in vitro}$ has to cope with several problems: $\bullit$ Glycosyltransferases are expressed only in very small activities. For large scale production, recombinant cell lines are needed. $\bullit$ Alternatively, enzymes catalyzing hydrolysis reactions $\textit{in vivo}$, for example galactosidases, can be used for synthesis. In this case, yields are usually very low. $\bullit$ Activated sugars (Nucleotide sugars) are very expensive substrates - up to DM 100,000 pre gramm [...