6E2B

Ubiquitin in complex with Pt(2-phenilpyridine)(PPh3)

Summary for 6E2B

• Entry DOI: 10.2210/pdb6e2b/pdb
• Descriptor: Ubiquitin, SULFATE ION, GLYCEROL, ... (5 entities in total)
• Functional Keywords: cyclometallated platinum (ii) complex, ubiquitin, platinum coordination, protein binding
• Biological source: Bos taurus (Bovine)
• Total number of polymer chains: 6
• Total formula weight: 54715.13

Authors

Zhemkov, V.A.,Kim, M. (deposition date: 2018-07-11, release date: 2018-11-14, Last modification date: 2023-10-11)

Primary citation

Solomatina, A.I.,Chelushkin, P.S.,Abakumova, T.O.,Zhemkov, V.A.,Kim, M.,Bezprozvanny, I.,Gurzhiy, V.V.,Melnikov, A.S.,Anufrikov, Y.A.,Koshevoy, I.O.,Su, S.H.,Chou, P.T.,Tunik, S.P.
Reactions of Cyclometalated Platinum(II) [Pt(N∧C)(PR3)Cl] Complexes with Imidazole and Imidazole-Containing Biomolecules: Fine-Tuning of Reactivity and Photophysical Properties via Ligand Design.
Inorg Chem, 58:204-217, 2019

PubMed Abstract: This work describes interaction of a family of [Pt(NC)(PR)Cl] complexes with imidazole (Im), possible application of this chemistry for regioselective labeling of proteins through imidazole rings of histidine residues and employment of the resulting phosphorescent products in bioimaging. It was found that the complexes containing aliphatic phosphines display reversible substitution of chloride ligand for imidazole function that required considerable excess of imidazole to obtain full conversion into the substituted [Pt(ppy)(PR)(Im)] product, whereas the substitution in the complexes with aromatic phosphines readily proceeds in 1:1.5 mixture of reagents. Rapid, selective, and quantitative coordination of imidazole to the platinum complexes enabled regioselective labeling of ubiquitin. X-ray protein crystallography of the {[Pt(ppy)(PPh)]/ubiquitin} conjugate revealed direct bonding of the platinum center to unique histidine-68 residue through the nitrogen atom of imidazole function, the coordination being also supported by noncovalent interaction of the ligands with the protein secondary structure. The variations of the cyclometalating NC ligands gave a series of [Pt(NC)(PPh)Cl] complexes (NC = 2-phenylpyridine, 2-(benzofuran-3-yl)pyridine, 2-(benzo[b]thiophen-3-yl)pyridine, methyl-2-phenylquinoline-4-carboxylate), which were used to investigate the impact of NC-ligand onto photophysical properties of the imidazole complexes and conjugates with human serum albumin (HSA). The chloride ligand substitution for imidazole and formation of the conjugates results in ignition of the platinum chromophore luminescence with substantially higher quantum yield in the latter case. Variation of the metalating NC-ligand made possible the shift of the emission to the red region of visible spectrum for both types of the products. Cell-viability tests revealed low cytotoxicity of all {[Pt(NC)(PPh)Cl]/HSA} conjugates, while PLIM experiments demonstrated their high potential for oxygen sensing.

PubMed: 30376305
DOI: 10.1021/acs.inorgchem.8b02204

Experimental method

X-RAY DIFFRACTION (1.45 Å)