title: Effect of motional restriction on the unfolding properties of a cytochrome c featuring a His/Met-His/His ligation switch.
abstract: The K72A/K73H/K79A variant of cytochrome c undergoes a reversible change from a His/Met to a His/His axial heme ligation upon urea-induced unfolding slightly below neutral pH. The unfolded form displays a dramatically lower reduction potential than the folded species along with a pseudo-peroxidase activity. We have studied electrochemically the effects of urea-induced unfolding on the protein electrostatically immobilized on an electrode surface functionalized by means of a negatively charged molecular spacer. The latter mimics the electrostatic interaction with the inner mitochondrial membrane. This behavior has been compared with the unfolding of the same species in solution. This system constitutes a model to decipher the role of the above electrostatic interaction in the unfolding of cytochrome c at physiological pH upon interaction with the membrane component phospholipid cardiolipin in the early stages of the apoptosis cascade. We found that immobilization obstacles protein unfolding due to structural constraints at the interface imposed by protein-SAM interaction.
authors: Department of Life Sciences, University of Modena and Reggio Emilia, via Campi 183, 41125 Modena, Italy. marco.sola@unimore.it.
authors: Antonio
authors: A
authors: Ranieri
authors: Carlo A
authors: CA
authors: Bortolotti
authors: Gianantonio
authors: G
authors: Battistuzzi
authors: Marco
authors: M
authors: Borsari
authors: Licia
authors: L
authors: Paltrinieri
authors: Giulia
authors: G
authors: Di Rocco
authors: Marco
authors: M
authors: Sola
mesh_terms: D045304:Cytochromes c / Q000737:chemistry*; D005656:Fungal Proteins / Q000737:chemistry*; D006418:Heme / Q000737:chemistry*; D055767:Immobilized Proteins / Q000737:chemistry*; D007700:Kinetics; D008958:Models, Molecular; D009038:Motion; D011487:Protein Conformation; D058767:Protein Unfolding; D012996:Solutions; D055672:Static Electricity; D014508:Urea / Q000737:chemistry; D015003:Yeasts / Q000737:chemistry*
chemical_list: D005656:Fungal Proteins; D055767:Immobilized Proteins; D012996:Solutions; D006418:Heme; D014508:Urea; D045304:Cytochromes c