The interactions of cis- and trans-diammineplatinum compounds with 5′-guanosine monophosphate and 5′-deoxyguanosine monophosphate. A proton nmr investigation

Abstract

The interactions of cis- and trans-diammineplatinum compounds with 5′-GMP and 5′-dGMP in dilute aqueous solution at neutral pH were investigated by 1H nmr. In addition to the 1:2 Pt nucleotide complexes cis- and trans-Pt(NH 3) 2(GMP) 2, it was possible to study the formation of the 1:1 Pt-nucleotide complexes with either one coordinated water or chloride ion. At 5°C GMP reacts with a stoichiometric amount of cis-diaquodiammine-platinum to yield cis-Pt(NH 3) 2(GMP) (H 2O) as a sole reaction product. From the present results it is concluded that such a complex may play an important role as the initial reaction product between antitumor compounds like cis-Pt(NH 3) 2Cl 2 and guanine in DNA in living organisms. The coupling constant 3J(H(1′)-H(2′)) of the H(1′) sugar proton in cis-Pt(NH 3) 2(GMP) 2 is temperature dependent, indicating a conformational change in the sugar moiety.