Side-chain control of beta-peptide secondary structures.

As one of the most important families of non-natural polymers with the propensity to form well-defined secondary structures, the beta-peptides are attracting increasing attention. The compounds incorporating beta-amino acid residues have found various applications in medicinal chemistry and biochemistry. The conformational pool of beta-peptides comprises several periodic folded conformations, which can be classified as helices, and nonpolar and polar strands. The latter two are prone to form pleated sheets. The numerous studies that have been performed on the side-chain dependence of the stability of the folded structures allow certain conclusions concerning the principles of design of the beta-peptide foldamers. The folding propensity is influenced by local torsional, side-chain to backbone and long-range side-chain interactions. Although beta-peptide foldamers are sensitive to solvent, the systematic choice of the side-chain pattern and spatiality allows the design of the desired specific secondary structure. The application of beta-peptide foldamers may open up new directions in the synthesis of highly organized artificial tertiary structures with biochemical functions.