Stability of the B conformation in wet-spun films of CaDNA.

Highly oriented, wet-spun films of CaDNA have studied via Raman spectroscopy as a function of both water content and excess CaCl$_{2}$ concentration. The secondary structure of the double-helical DNA can be determined by monitoring the conformationally-sensitive vibrational modes at 807 cm$^{-1}$ for A-DNA and 834 cm$^{-1}$ for B-DNA. We find that the DNA molecules are in the B conformation between relative humidities of 98$\%$ and 75$\%$ for all salt contents.