Stability of a ferryl-peptide conjugate is controlled by a remote substituent.
The formation of a synthetic ferryl-peptide conjugate and mechanistic studies that elucidate its mode of decomposition are presented. A ferryl species is generated from a ligand-dipeptide conjugate 4. The ferryl species [Fe(IV)(4)(O)](2+), noted as compound 5, was characterized by UV-vis spectroscopy and by high-resolution electrospray mass spectrometry. The ferryl-peptide conjugate 5 is stable for over 1 h at room temperature. Ester derivatives of 5 decay at different rates, consistent with the remote ester group controlling the stability of the ferryl. The kinetic isotope effect value (4.5) and rho = -1.3 observed with ester derivatives suggest that the mechanism for decomposition of 5 follows a hydrogen-atom-transfer pathway. The formation and decay of 5 was fit to a two-step process, with the decay being unimolecular with respect to the ferryl 5.
Jabre
Nitinkumar D
ND
Department of Chemistry and Central Instrumentation Facility, Wayne State University, 5101 Cass Avenue, Detroit, Michigan 48202, USA.
Hryhorczuk
Lew
L
Kodanko
Jeremy J
JJ
D007501:Iron / Q000737:chemistry*; D007700:Kinetics; D008024:Ligands; D015394:Molecular Structure; D010455:Peptides / Q000737:chemistry*
D008024:Ligands; D010455:Peptides; C066317:ferryl iron; D007501:Iron