Proton nuclear overhauser effect study of the structure of an actinomycin D complex with a self-complementary...

Saturation transfer and nuclear Overhauser effect (NOE) techniques have been used to assign some resonances of nonexchangeable protons in the NMR spectrum of the complex formed between actinomycin D and the self-complementary tetranucleoside triphosphate d(A-G-C-T). Intermolecular NOEs suggest that the drug chromophore intercalates between the two G-C base pairs of the nucleotide double helix, while the pentapeptide lactone rings fill the minor groove. Binding-induced distortions of helix geometry are discussed.