Spectral changes of nucleic acids and nucleotide solutions at the 190-220nm region

Nucleic acids and nucleotide solutions have between 190 and 220 nm an hypo-bathochromic effect electrostatistically induced by acylic groups or by effective binding of several substances. In the former case, with DNA or RNA, the effect reverts through gel filtration and dialysis. In the latter case no reversion occurs. This is proposed as a probe for complex formation with the nucleic acid bases. Thermal denaturation of DNA solutions gives to the above mentioned maximum, an hyperchromicity somewhat different from the usually obtained at 260 nm.