Poly[d(A‐T)‐Cs⁺] conformations studied by IR spectroscopy

Abstract

Abstract Infrared absorption and ir linear dichroism measurements have been performed on poly[d(A‐T)‐Cs + ] films at various relative humidities. At high relative humidity, samples are in a B form; at low relative humidity, in a C form. The B → C conformational transition is shown to be a noncooperative one corresponding to a gradual evolution of the backbone geometry of the polynucleotide within the B family. the C‐form‐type spectrum is characteristic of an alternated phosphodiester chain with a dinucleotidic repeat unit.