Cellulose is the most abundant polysaccharide on earth and it is relatively a simple homopolymer with three hydroxyl groups, differing only subtly in reactivity. The position of substitution has a powerful influence on physical properties of cellulose derivatives. To better understand the structure and property relationships of cellulose derivatives, it is critical to have all homopolymers related to important cellulose ethers and esters available. However, regiocontrol in cellulose chemistry is still a difficult, mostly unconquered frontier. In this dissertation, the main objective is to develop novel synthetic methods to synthesize regioselectively substituted cellulose derivatives including cellulose ethers and esters, and apply advanced characterization tools to understand structure and its influence on properties, which will give us deep insights into the composition of more random commercial derivatives, maximizing the content of advantageous monosaccharides. Several strategies to regioselectively synthesize cellulose derivatives are discussed in detail. The obtained regioselective cellulose derivatives were fully characterized analytically. Structure-property relationships of these regioselectively substituted cellulose derivatives were also studied. / Ph. D.

Mucin is a term used to describe a large family of heavily glycosylated proteins which are present on the surfaces of secretory epithelial cells and are overexpressed by many carcinomas. Membrane-bound mucin MUC1 is of special interest. Its backbone consists of repeating units of twenty amino acids with five potential glycosylation sites. These sites are expanded to structures like the T (Galβ(1->3)GalNAcα-Ser/Thr) and Tn (GalNAcα-Ser/Thr) antigens by the action of various glycosyltransferases. In different types of carcinomas these epitopes are being terminated by sialic acid residues to form among others: 2,3-sialyl-T and sialyl-Tn structures due to the elevated levels of different sialyltransferases. Solid-phase synthesis of the selected antigens derived from the mucin MUC1 has been developed and optimized. A chemoenzymatic approach has been used to effectively prepare 2,3-sialyl-T and 2,6-sialyl-Tn glycopeptides. The formation of intramolecular sialic acid lactones in presence of acetic acid was investigated. The stability of lactones formed from 2,3-sialyl-T towards water was studied using NMR spectroscopy and it appeared that 1''->2' lactone displayed remarkable strength to hydrolysis and it was suggested as a candidate for cancer vaccine. Gel-phase 19F NMR spectroscopy is known to be a very good tool to characterize resin-bound products using fluorinated protecting groups and linker molecules. The hydrophobic peptide LLLLTVLTV, which is a fragment from the MUC1 signal sequence, was prepared using solid-phase synthesis according to a modified Fmoc protocol with more active coupling reagent, stronger base, and the isopropylidene dipeptide Fmoc-Leu-Thr-(ΨMe,Mepro)-OH. Gel-phase 19F NMR spectroscopy was used to evaluate peptide chain aggregation and coupling and deprotection efficiency. A carbamate linker strategy proved to be effective in solid-phase synthesis of serine-based neoglycolipids with terminal amino functionality. Neoglycolipids were covalently bound to secondary amines in microtiter plates using squaric acid ester methodology. These arrays have potential to study the interactions between carbohydrates and e.g. proteins and microbes. The new fluorinated α-amino protective group [1-(4-(4-fluorophenyl)-2,6-dioxocyclohexylidene)ethyl] Fde was developed. This group is cleaved with hydrazine in DMF solution. By using amino acids protected with this group, it was possible to quantify the efficiency of peptide coupling using gel-phase 19F NMR spectroscopy.