structural communications
Crystals of HEWL with cisplatin and HEWL with carboplatin grown in sodium iodide conditions both show a partial chemical transformation of cisplatin or carboplatin to a transiodoplatin (PtI2X2) form. The binding is only at the Nδ atom of His15. A further Pt species (PtI3X) is also seen, in both cases bound in a crevice between symmetry-related protein molecules.
structural communications
The platinum hexahalides have an octahedral arrangement of six halogen atoms bound to a Pt centre, thus having an octahedral shape that could prove to be useful in interpreting poor electron-density maps. In a detailed characterization, PtI6 chemically transformed to a square-planar PtI3 complex bound to the Nδ atom of His15 of HEWL was also observed, which was not observed for PtBr6 or PtCl6.
structural communications
An X-ray crystal structure showing the binding of purely carboplatin to histidine in a model protein has finally been obtained. This required extensive crystallization trials and various novel crystal structure analyses.