This potent Pt(II) complex (FW = 505.82 g/mol; CAS 1416900-51-0), also known as cis-diamminephenanthridinechloroplatinum(II), penetrates cell membranes either by passive diffusion or carrier-mediated active transport, with the hydrophobic ligand maximizing cellular uptake and making it cytotoxic compared with cisplatin and carbinatoplatin. Its molecular structure was designed with based the X-ray structure of RNA polymerase II (Pol II), when stalled at a monofunctional pyriplatin-DNA adduct. Phenanthriplatin interacts with guanine residues, forming highly potent, monofunctional DNA adducts. While many Pol II elongation complexes stall after successful addition of CTP opposite the phenanthriplatin-dG adduct in an error-free manner, a few slowly undergo error-prone bypass of the phenanthriplatin-dG lesion, a behavior that resembles DNA polymerases that similarly switch from high-fidelity replicative DNA processing (errorfree) to low-fidelity translesion DNA synthesis (error-prone) at DNA damage sites
