Nanometer-Range Communication of Stereochemical Information by Reversible Switching of Molecular Helicity

摘要

Stable helical molecular structures are ubiquitous in both biological and synthetic polymers, and in general the handedness (screw-sense) of a helical polymer is dictated by the chirality of the monomers from which it is built (for example, DNA built from D-deoxyribose is typically right-handed, as are a helices built from L-amino acids). It occurred to us that the switching of a molecular helix between a left- and a right-handed form could constitute a very simple means of communicating information along the axis of the helix over distances commensurate with the helical cooper-ativity length. Changes in conformation are commonly used by biological systems to communicate information, for example, in receptors or in allosteric proteins. However, simple switching between two helical forms of a typical peptide is not suitable for such a purpose because of the substantial difference in stability between diastereoisomeric helices built from chiral monomers. There are, however, many synthetic oligomers which favor helical structures even though they are constructed from nonchiral subunits. We exploited one of these classes of oligomers in this study.