Mechanism of the reversal reaction of platinated DNA with thiourea studied by platinated 5'-GMP

The reversal reactions of cis-Pt(NH3)2(5'-GMP)2] 2-(1) and trans-Pt(NH3)2(5'-GMP)2] 2-(2) with thiourea were examined by reversed phase HPLC and monothioureido intermediate cis-Pt(NH3)2(5'-GMP) (tu)] (4) was detected. This result suggested that Pt-5'-GMP-N(7)] bond was more labile than Pt-NH3 bond and the release of ammonia from cis-Pt(II)-DNA base complexes is a result of trans-labilizing effect of sulfur containing molecule displaced with DNA base.