Polypeptide Polar Liquid Crystals and Second-Harmonic Generation Analysis

摘要

@@Rigidity and chirality are topical characteristics of α-helical polypeptides and explain the tendency for polypeptide molecules to form a cholesteric liquid crystal (LC) in concentration solutions1. One feature of polypeptide helices, the polarity, is also important. Since the helical conformation of polypeptides is built up by intramolecular hydrogen bonds between the proton donor N-H group and the proton accepter C=O group, residue dipole components accumulate along the polymer chain, producing an extremely large dipole moment, μ; for example, μ = 4000D for an α-helix with a degree of polymerization of 10002. Theoretical calculations and computer simulations3 predict the existence of polar (or ferroelectric) nematic phase in which polar molecules align with the same directionality of polar axis although no experimental example has been reportedso far.