Identification of a unique ethidium bromide binding site on yeast tRNAPhe by high resolution (300 MHz) nuclear magnetic resonance.

The binding of ethidium bromide to yeast tRNAPhe has been studied by high resolution (300 MHz) proton nuclear magnetic resonance. Under appropriate experimental conditions one ethidium bromide is bound to each tRNA and two resonances from ring NH protons are shifted upfield. These observations taken in conjunction with the low-field spectrum of yeast tRNAPhe show that the unique ethidium bromide binding site is located between base pairs AU6 and AU7 of the amino acid acceptor stem. This information should be of value in understanding the way in which ethidium bromide binding alters the biochemical properties of the tRNA molecules.