Infrared spectra of formamide-treated nucleic acids.

The effects of formamide treatment on the infrared absorption of sodium salts of calf thymus DNA, yeast ribosomal RNA, and yeast soluble RNA have been examined. The effects are found to be very similar to the effects of heating the aqueous solutions of these sodium salts of the nucleic acids. On the basis of the characters of the absorption bands where these effects are observed, it is concluded that the formamide treatment causes a cleavage of the base pairings, a change in the electronic structure of the base portions and a change in the molecular conformation of the phosphate and sugar portions of NaDNA.