Recognition and estimation of 5-methylcytosine in nucleic acids

Abstract

An aminopyrimidine which on deamination gives rise to thymine was discovered as a new constituent of some desoxypentose nucleic acids (DNA). The u.-v. absorption spectra and chromatographic behavior are identical with those of synthetic 5-methylcytosine, and the tentative conclusion is drawn that it is the latter. By a simple chromatographic technic, this pyrimidine can be estimated when occurring in amounts as small as 0.1% of a nucleic acid. U.-v. absorption spectra of 5-methylcytosine were determined. The new pyrimidine occurs in amts. characteristic of the source in all of the animal DNA''s and the one plant DNA analyzed, but is apparently lacking from DNA of bacteria and viruses, and from ribonucleic acids.