N- versus C-Terminal Control over the Screw-Sense Preference of the Configurationally Achiral, Conformationally Helical Peptide Motif Aib8GlyAib8

摘要

Helical conformations are commonly adopted by both biologicalnand synthetic polymers, and the chirality of the monomers fromnwhich they are built generally determines the screw sense of thenhelix.1 The amino acid aminoisobutyric acid (Aib), while stronglynpromoting the adoption of helical peptide conformations,2 is achiral,nand otherwise achiral oligomers containing Aib can be induced tonprefer one of the two screw senses by ligation with a single terminalnamino acid.3,4 In this work, we have used a simple NMR methodnto show that screw-sense control is more effective when appliednfrom the N-terminus rather than from the C-terminus. We also reportnthe crystal structure of nearly six full turns of a peptide 310 helix,nthe longest 310 helix ever observed in the crystalline state.