evidence is presented showing that the ethidium dimer bisintercalates into poly ( da-dt ) in high salt , based on the observation that i ) dimer and monomer ring protons exhibit similar upfield shifts upon dna binding , ii ) upfield shifts of dna sugar protons are twice as large with the dimer than with ethidium bromide .
C0015008
ethidium
C0019873
ethidium bromide