ic000299m_si_001.pdf (82.83 kB)
EPR Spectroscopic Studies of the Reduction of Chromium(VI) by Methanol in the Presence of Peptides. Formation of Long-Lived Chromium(V) Peptide Complexes
journal contribution
posted on 2000-12-07, 00:00 authored by Henrietta A. Headlam, Peter A. LayThe synthesis and characterization of the first Cr(V) complexes with non-sulfur-containing peptides, which may
mimic the chemistry of the intermediates in the formation of Cr-induced peptide−DNA cross-links in vivo, are
reported. The reduction of Cr(VI) with methanol in the presence of a number of non-sulfur-containing peptides
produced relatively stable Cr(V)−peptide complexes, which were characterized by EPR spectroscopy and
electrospray mass spectrometry. The reaction of Cr(VI) with methanol alone (in the absence of peptide ligands)
resulted in the formation of two Cr(V)−methanol intermediates, with giso values of 1.9765 and 1.9687. The methanol
reduction of Cr(VI) in the presence of the glycine peptides, triglycine, tetraglycine, and pentaglycine resulted in
the formation of both Cr(V)−methanol and Cr(V)−peptide intermediates, while only the Cr(V)−peptide complexes
were detected in the reactions with the alanine peptides trialanine, tetraalanine, and pentaalanine. Similar EPR
signals were observed for all of the Cr(V)−peptide complexes with giso values between ∼1.986 and ∼1.979, and
AN values of (2.1−2.6) × 10-4 cm-1.