Peculiar mechanistic and structural features of the carboplatin-cytochrome c system revealed by ESI-MS analysis.
Carboplatin (CPT), today the most important platinum(II) anticancer drug, manifests an extreme kinetic inertness, in vitro, at physiological pH; the actual mechanisms for its activation inside cells are still poorly understood. We show here that horse heart cytochrome c reacts with CPT, leading to the formation of stable platinum/protein adducts. The two major CPT-cytochrome c species resulting from the aforementioned reaction were characterised by electrospray ionisation mass spectrometry (ESI-MS). Notably, both these adducts have the ability to react with guanosine 5'-monophosphate (5'-GMP), giving rise to the respective cytochrome c-CPT-5'-GMP ternary complexes. Additional ESI-MS measurements on enzymatically cleaved cytochrome c adducts suggest that protein platination probably occurs at Met65. The mechanistic implications of these findings are discussed.
Gabbiani
Chiara
C
Department of Chemistry, University of Florence, Via della Lastruccia 3, 50019, Sesto Fiorentino, Italy.
Casini
Angela
A
Mastrobuoni
Guido
G
Kirshenbaum
Noam
N
Moshel
Ofra
O
Pieraccini
Giuseppe
G
Moneti
Gloriano
G
Messori
Luigi
L
Gibson
Dan
D
D000970:Antineoplastic Agents / Q000737:chemistry*; D016190:Carboplatin / Q000737:chemistry*; D006152:Cyclic GMP / Q000737:chemistry; D045304:Cytochromes c / Q000737:chemistry*; D006863:Hydrogen-Ion Concentration; D021241:Spectrometry, Mass, Electrospray Ionization
D000970:Antineoplastic Agents; D045304:Cytochromes c; D016190:Carboplatin; D006152:Cyclic GMP