Sugar-peptide structures synthesis

The aim of this report is to collect the most important results in sugar studies by NMR methods in the last two years. This review covers determination of new and previously known structures of sugars isolated from natural sources, as well as the structures of carbohydrates obtained by chemical or enzymatic synthesis. Moreover, we have included herein the papers describing non-covalent interactions between carbohydrates and other sugars, peptides, proteins and DNA fragments, as well as the application of NMR techniques to identification and quantification of sugars. The development in rare and unusual NMR methods used to study the sugar structures is also included. The last section focuses on the computational methods used to calculate NMR parameters, and on the carbohydrate databases. 

Insulin is a polypeptide hormone that consists of two peptide chains bonded by two disulfide bonds. The two chains are designated A and B. The A chain consists of 21 amino acids with a third internal disulfide bond, and the chain contains the remaining 30 amino acids. All vertebrates produce insulin and the structure is similar in these species. For example, the insulin produced in humans and porcine species differs by only one amino acid, and humans and bovine insulin differ by three amino acids. Insulin plays a crucial role in several physiological processes. These include the regulation of sugar in the body, fatty acid synthesis, formation of triglycerides, and amino acid synthesis. 

Carbohydrate structures can also act as a scaffold for dendrimer formation. The polysubstituted sugar 23 (Fig. 5) has been synthesized and shown that it can act as a scaffold onto which peptide sequences can be assembled to form another novel vaccine system (15). The development of this carbohydrate scaffold technology and its application to vaccine and gene delivery is under way. The synthesis of 23 is complex a complete account of the procedures can be found in ref. 15. 

There is increasing interest in the development of foldamers or polymeric structures that can adopt organised secondary structures like those of proteins, nucleic acids and some polysaccharides [42]. Sugar amino acid-based foldamer research has so far been primarily concerned with synthesis of polymers with secondary sfructural features. Such foldamers may find application as scaffolds for peptidomimetic development if they adopt turn, helical and strand sfructures observed for peptides or if derivatives can act as ligands for peptide receptors ... 

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