Bomar, M. G., Song, B., Kibler, P., Kodukula, K., & Galande, A. K. (2011). An enhanced β turn in water. Organic Letters, 13(21), 5878-5881.
Aiming to design short linear peptides featuring strong intramolecular hydrogen bonds in water, a series of tetrapeptides based on the sequence Ac-Ala-Pro-Ala-Ala-NH2 containing all possible combinations of l- and d-amino acids was synthesized. A regiospecific combination of heterochiral residues (ddll or its mirror image lldd) can be used to increase turn formation and stability within short peptides in water.