EXPLORING METAL COMPLEXES-PROTEIN/PEPTIDE
INTERACTIONS BY HIGH RESOLUTION MASS
SPECTROMETRY
Elena Michelucci1, Chiara Gabbiani2, Angela Casini3, Giuseppe Pieraccini1, Gloriano
Moneti1, Daniela Valensin4, Luigi Messori2
1Centro Interdipartimentale di Spettrometria di Massa (CISM), Universitá di Firenze, Via U. Schiff 6,
50019 Sesto Fiorentino, Italy
2Dipartimento di Chimica, Universitá di Firenze, Via della Lastruccia 3, 50019 Sesto Fiorentino, Italy 3Institut des Sciences et Ingénierie Chimiques, Ecole Polytechnique Fédérale de Lausanne (EPFL), 1015
Lausanne, Switzerland
4Departimentro di Chimica, Universitá di Siena, Via A. Moro 2, 53100 Siena, Italy
Electrospray ionization high resolution mass spectrometry was used to explore the interactions occurring between metal complexes and proteins/peptides.
In a first study three medicinally relevant compounds, cisplatin, transplatin and the organometallic ruthenium compound RAPTA-C, were reacted with a pool of three proteins, ubiquitin, cytochrome c and superoxide dismutase, and the reaction products were analysed using high resolution mass spectrometry. The formation of metal-protein adducts was clearly observed for the three proteins. In addition, valuable information was obtained on the nature of the protein-bound metallofragments, on their distribution among the three different proteins and on the binding kinetics. The platinum compounds were less reactive and considerably less selective in protein binding than RAPTA-C, which showed a high affinity towards ubiquitin and cytochrome c, but not superoxide dismutase. In addition, competition studies between cisplatin and RAPTA-C showed that the two metallodrugs upon protein binding manifest high affinity for the same amino acid residues.
In a second study the ruthenium complex fac-[Ru(CO)3Cl2(N1-thz)] was reacted with two
peptides, human β amyloid 1-42 and human β amyloid 1-28, and the reaction products were analysed using high resolution mass spectrometry. The MS spectra suggested a prevalent 1:1 metal-peptides stoichiometry and disclosed the nature of peptide-bound metallic fragments.
