Fluorometric studies of: I. daunomycin and myricetin interactions with l-tryptophyl-l-trytophan, l-tryptophyl-l-tyrosine, and adenosine triphosphate II. daunomycin-deoxyribonucleic acid interactions in the presence and absence of divalent metal ions

摘要

Fluorescence quenching has been used to study the interactions of daunomy cin and myricetin with various quenchers — adenosine triphosphate (ATP), L tryptophyl- L-tryptophan, L-tryptophyl-L-tryosine myosin, and deoxyribonucleic acid (DNA), at various pH levels. DNA, although producing a quenching effect on the fluorescence of daunomycin, enhanced the fluorescence of myricetin. Fluore scence quenching has also been used to study the interactions of DNA in the presence and absence of divalent metal ions, with daunomycin. The values of the Stern-Volmer quenching constant (ksy), and static quenching constants (V) obtained, indicate that the quenching of daunomycin and myricetin fluorescence by the quenchers studied proceed via collisional, static, as well as, selective quenching mechanisms, and that they are good quenchers for daunomycin fluorescence. The studies also revealed the pH-dependence of daunomycin fluorescence quenching. Physiologically high levels of Fe++, Cu++, and Mg++, increased the apparent association contant (K ) for daunomycin-DNA complex, and changed the number app of available binding sites per drug molecule. The addition of Fe+ , Mg and Cu+ did not produce any change in the binding site model of daunomycin-DNA.