Effect of polydispersity on the n.m.r. spectra of poly(γ-benzyl-l-glutamate) through the helix → coil transition

Abstract High resolution n.m.r. and o.r.d. measurements on unfractionated poly(γ-benzyl- l -glutamates) have been compared with results obtained on fractionated samples obtained therefrom by precipitation chromatography. It is concluded that the prime cause of the ‘double-peak’ main chain proton resonances observed in the helix-coil transition region is conformational heterogeneity resulting from molecular weight polydispersity.