SummaryAddition of DNA (but not RNA) to solutions of lysergic acid diethylamide resulted in a depression of the absorption and fluorescence spectra of the drug. The Kd for D-LSD: DNA binding, calculated from spectral changes, was 5 × 10-4 M, and each nucleotide residue was a potential binding site. Binding did not occur at pH 3 (where DNA is nonhelical), and was decreased by prior heating of...