Orientation of poly-L-lysine hydrobromide by magnetic fields

Abstract

Very slow cooling of poly-L-lysine hydrobromide solutions in the magnetic field of an n.m.r. spectrometer produced gelled samples in which the long axes of the poly-L-lysine α-helices were oriented parallel to the magnetic field, but remained fixed in the sample (thus allowing alteration of the angle between the long axes and the field by rotation of the sample). This alignment was detected by n.m.r. and by the anisotropy of the optical density. The orientation is due to anisotropy of the magnetic susceptibility of the hexagonally-packed α-helices, and shows that each hexagonal array must involve ≳ 5 × 10⁵ molecules.