Oligosaccharides terms Links

The term monomeric mechanism will be used for the mechanism depicted in the left-hand part of Scheme 2 (sequence a). In this case, the monosaccharide residues are transferred consecutively from the corresponding glycosyl donors (Z-A or Z -B) onto a membrane-bound glycosyl acceptor. The acceptor is generally a monosaccharide residue, which may be a fragment of an oligosaccharide chain linked to a hydrophobic molecule embedded in a cell membrane. In many instances, the acceptor that is used for assembly of the polymeric chain (Y) is not identical to the final acceptor (X) of the chain, and further transfer of the chain from Y to X, or liberation of the polysaccharide molecule in the case of exocellular polysaccharides, is a necessary step in the biosynthesis. 

Cyclic oligosaccharides composed of a single type of oligosaccharide unit may be named semisystematically by citing the prefix cyclo , followed by terms indicating the type of linkage [e.g. malto for a-(l—>4)-linked glucose units], the number of units (e.g. hexa for six) and the termination -ose . The trivial names a-cyclodex-trin (a-CD) for cyclomaltohexaose, (i-cyclodextrin ((i-CD) for cyclomaltoheptaose and y-cyclodextrin (y-CD) for cyclomaltooctaose are well established. 

Describe in general terms the process by which N-linked oligosaccharides are synthesized and attached to proteins. What are the functions of the ER and the Golgi ... 

Figure 1 represents the general structure of Salmonella lipopolysaccharides. They contain an external polysaccharide, the O-antigenic chain, and an innermost component, termed lipid A. O-chain and lipid A are linked to each other by an oligosaccharide referred to as the core. O-Specific Chains. As indicated in Figure 1, O chains are in general made up of repeating units of di-, tri-, or higher oligosaccharides. In rare cases the O-chain is a homopolysaccharide. The structure of the O-chain is unique to each bacterial serotype great diversity is encountered in the structures of O-chains.

For many years this laboratory has been studying the interactions of concanavalin A (con A), a carbohydrate binding protein of considerable interest (X—4 ), with simple and complex carbohydrates (578)- It was established that compared to monosaccharides, oligosaccharides composed of a- (l- -2)-linked D-roannose units exhibited an enhanced affinity for con A (9). This increased affinity for con A was explained both in terms of an extended binding site (5,10) and a statistical mode (11). 

---