On the cooperative and noncooperative binding of ethidium to DNA

Abstract

The equilibrium binding of ethidium bromide to native DNAs and to poly(dG-dc).poly(dG-dC) has been studied by both phase partition and direct spectrophometric techniques. The binding isotherms obtained from both experimental techniques show that ethidium binds in a cooperative manner to E.coli DNA. on the other hand, no evidence of coperative binding was observed in the binding isotherms obtained with calf thymus,C. perfringens, M.Lysodeikticus, or poly(dG-dC). (dG-dC) under the experimental conditions used (0.1 M Nacl). © 1982 IRL Press Limited.