title: The nature of inactivating lesions produced by platinum(II) complexes in phage lambda DNA.
abstract: Lambda DNA loses transfectivity and acquires interstrand cross-links after treatment with either trans-Pt(II) or cis-Pt(II). With trans-Pt(II) there is close to an equivalence between the fraction of lambda DNA cross-linked and the fraction inactivated. In contrast, with cis-Pt(II) there are approx. 5 inactivating lesions for each lambda DNA interstrand cross-link. These results suggested that trans-PT(II) does not introduce intrastrand inactivating lesions into lambda DNA while cis-Pt(II) does so. To verify this conclusion, the cross-linked and uncross-linked fractions of lambda DNA treated with trans-PT(II) or cis-Pt(II) were separated on alkaline sucrose gradients. After trans-Pt(II) treatment, the uncross-linked fraction of lambda DNA was transfective when renaturated. However after cis-Pt(II) treatment the uncross-linked fraction of lambda DNA was not transfective when renatured. Thiourea treatment restored transfectivity to all inactivated fractions, showing that these lesions are reversible. We conclude that trans-Pt(II) inactivates lambda DNA primarily by introducing interstrand cross-links but that cis-Pt(II), although it also introduces interstrand cross-links, inactivates lambda DNA primarily by introducing intrastrand lesions.
mesh_terms: D010582:Bacteriophage lambda / Q000187:drug effects / Q000235:genetics*; D002499:Centrifugation, Density Gradient; D004279:DNA, Viral / Q000378:metabolism*; D009691:Nucleic Acid Denaturation; D013237:Stereoisomerism; D013890:Thiourea / Q000494:pharmacology; D014162:Transfection
chemical_list: D004279:DNA, Viral; D013890:Thiourea