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Carbohydrates are the most abundant of all natural products. They show
great structural variation which is reflected in a wide range of biological
functions.1-4
Their role as structural material and in metabolism has long
been recognised. Much of current research is, however, directed towards
cell surface saccharides which are of importance for cell recognition and
immunology. Capsular polysaccharides (CPS) and lipopolysaccharides
(LPS), which surround some bacteria, 5
are often immunogenic and
antibodies against these are used for diagnostics. Oligosaccharides on the
surface of mammalian cells are involved in cell differentiation and
recognition and may also serve as attachment sites for bacteria. 6
The
presence of unusual oligosaccharides is often associated with tumours.7
Polysaccharides used in medicine include, e.g. dextran as a plasma
substitute, hyaluronic acid in eye-surgery and heparin to prevent blood
clotting. To understand the mechanisms of the various biological interactions of carbohydrates knowledge of both the primary and the secondary structure (conformation) is required. The first part of this thesis discusses the structural analysis of regular polysaccharides using results from component and linkage analysis together with NMR chemical shifts and the computer program CASPER for sequence determination. In the second part the conformational analysis of two monosaccharides with flexible side chains is performed using experimental (NMR-spectroscopy) and computational (molecular modeling) methods. |