STABILIZATION OF THE B-CONFORMATION IN UNORIENTED FILMS OF CALF THYMUS DNA BY NACL - A RAMAN AND IR STUDY

Unoriented films of calf thymus NaDNA with either 3.0 or 5.0 NaCl per base pair were prepared by dehydrating unstressed gels. These films we re studied by Raman and ir spectroscopy. The 5.0 samples showed very s trong vibrational modes characteristic of the B conformation at relati ve humidities (RH) as low as 30%, indicating that those samples were e ntirely in the B conformation. The 3.0 samples showed weaker features: some of the DNA in these samples were in the B conformation at 80% RH while the DNA is essentially in a disordered phase at 30% RH. (C) 199 7 John Wiley & Sons, Inc.