Restriction‐enzyme cleavage of DNA modified by platinum(II) complexes

Abstract

The effect of binding of cis-diamminedichloroplatinum(II), its trans isomer and diethylenetriaminechloroplatinum(I1) chloride to DNA on the splicing effectiveness of BamHI, EcoRI and SalI restriction endonucleases has been determined by means of gel electrophoresis. All three platinum complexes inhibit the cleavage of linearized plasmid DNA. In addition, the three platinum complexes bound to DNA constitute a barrier across which the linear diffusion of EcoRI on DNA is difficult. We interprete these findings to mean that the splicing effectiveness of restriction enzymes is influenced by bifunctional and monofunctional DNA adducts of platinum via both steric interference and DNA conformational distortions. Whereas the platinum adducts in the restriction sites or in their very close proximity inhibit the cleavage, the lesions occurring a greater distance from the restriction site can slow down the process of the localization of recognition sequences.

Rates of intercalator-driven platination of DNA determined by a restriction enzyme cleavage inhibition assay

“…We reasoned that the combined effects of these adducts would cause efficient inhibition of Eco RI-mediated DNA cleavage and the most pronounced measurable effect in a gel-based assay. Brabec and Balcarova [26] demonstrated in plasmid DNA randomly modified with platinum that although restriction enzyme cleavage is inhibited by adducts within or directly adjacent to the restriction sites, platinated residues at a greater distance are able to slow the recognition of the restriction site by the enzyme. To minimize this effect and to ensure that only cleavage inhibition by adducts localized to the restriction site were detected by the assay, the sequences 5′-CG and 5′GA, as well as other high-affinity sites, were omitted from both strands of the probe sequence.…”

Synthesis and potential cytotoxic activity of new phenanthrylphenol-pyrrolobenzodiazepines

“…Several reports in the literature have employed restriction endonuclease inhibition study to confirm the relative binding affinity of DNA interactive small molecule ligands [21][22][23]. A quantitative restriction enzyme digestion (RED 100 ) assay has been developed in which the inhibition of DNA cleavage by BamHI is used to probe the DNA binding capability of PBD monomers [24].…”

Linker Length Modulates DNA Cross-Linking Reactivity and Cytotoxic Potency of C8/C8‘ Ether-Linked C2-exo-Unsaturated Pyrrolo[2,1-c][1,4]benzodiazepine (PBD) Dimers

“…The solvent was evaporated under reduced pressure, and the resulting residue was subjected to flash chromatography (98:2 v/v CHCl3/MeOH) to give the bis-imine target molecule 4b as a pale orange glass which was repeatedly evaporated in vacuo with CHCl3 to provide the imine form. Yield ) 85 mg (75%); [R] D 20 ) +734°(c ) 0.05, CHCl3); 1 H NMR (400 MHz, CDCl3) δ 7.68 (d, 2H, J ) 4.4 Hz), 7.49 (s, 2H), 6.80 (s, 2H), 5.19 (br s, 2H), 5.16 (br s, 2H), 4.28 (br s, 4H), 4.15-4.00 (m, 4H), 3.92 (s, 6H), 3.90-3.80 (m, 2H), 3.12 (dd, 2H, J ) 9.0, 15.9 Hz), 2.95 (d, 2H, J ) 15.9 Hz), 2.00-1.85 (m, 4H), 1.72-1.67 (m, 2H); 13 Determination of In Vitro Cytotoxicity. K562 human chronic myeloid leukemia cells were maintained in RPM1 1640 medium supplemented with 10% fetal calf serum and 2 mM glutamine at 37 °C in a humidified atmosphere containing 5% CO 2 and were incubated with a specified dose of drug for 1 h at 37 °C in the dark.…”