A novel platinum reagent [chloro(2,2':6',2''-terpyridine)platinum(II) chloride] for use in heavy-atom derivatization of protein crystals

A platinum chromophore, chloro(2,2':6',2''-terpyridine)platinum(II) chloride, previously used in labelling active-site histidines of serine proteases, proves to be a useful reagent in heavy-atom derivatization of protein crystals for X-ray crystallographic phase determination.