Effects of ancillary ligands on selectivity of protein labeling with platinum(II) chloro complexes.

摘要

Potassium (2,6-pyridinedicarboxylato)chloroplatinate(II) was synthesized. The molecular structure of the complex in (n-Bu)(sub 4)N(Pt(dipic)Cl)(center dot)0.5H(sub 2)O was determined by x-ray crystallography. The (Pt(dipic)Cl)(sup (minus)) is essentially planar and contains a Pt(II) atom, a tridentate dipicolinate dianion ligand, and a unidentate Cl(sup (minus)) ligand. The bis(bidentate) complex trans-(Pt(dipic)(sub 2))(sup 2(minus)) was also observed by (sup 1)H NMR. A red gel-like substance was observed when the yellow aqueous solution of K(Pt(dipic)Cl) was cooled or concentrated. The K(Pt(dipic)Cl) molecules form stacks in the solid state and gel-like substance but remain monomeric over a wide range of concentrations and temperatures. The reactivity and selectivity of(Pt(dipic)Cl)(sup (minus)) toward cytochromes c from horse and tuna were studied. The new transition-metal reagent is specific for methionine residues. Di(2-pyridyl-(beta)-ethyl)sulfidochloroplatinum(II) chloride dihydrate was also synthesized. This complex labels histidine and methionine residues in cytochrome c. The ancillary ligands in these platinum(II) complexes clearly determine the selectivity of protein labeling. 106 refs., 10 figs., 11 tabs. (ERA citation 15:035959)