Polypyridine and polyamine mixed-ligand complexes of tripeptidonickel(III)

Pappenhagen, Thomas L.; Kennedy, W. R.; Bowers, Conrad P.; Margerum, Dale W.

doi:10.1021/ic00219a031

Cited by 12 publications

(3 citation statements)

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“…A frozen EPR spectrum in liquid N 2 and pH 0.7 exhibits signals at 2980 G ( g ⊥ = 2.25) and 3330 G ( g ∥ = 2.02, Figure S3). These g values are in agreement with those reported for other Ni(III)−peptide complexes. ,, …”

Section: Resultssupporting

confidence: 92%

Oxidative Self-Decomposition of the Nickel(III) Complex of Glycylglycyl-l-histidylglycine

et al. 2004

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Self-decomposition of the nickel(III) doubly deprotonated peptide complex of Gly2HisGly occurs by base-assisted oxidation of the peptide. At < or =p[H+] 7.0, the major pathway is a four-electron oxidation (via 4 Ni(III) complexes) at the alpha carbon of the N-terminal glycyl residue. The product of this oxidation is oxamylglycylhistidylglycine, which hydrolyzes to yield ammonia and oxalylglycylhistidylglycine. Both of these peptide products decompose to give isocyanatoacetylhistidylglycine. A small amount (2%) of oxidative decarboxylation also is observed. In another major pathway above p[H+] 7.0, two Ni(III)-peptide complexes coordinate via an oxo bridge in the axial positions to form a reactive dimer species. This dimer generates two Ni(II)-peptide radical intermediates that cross-link at the alpha carbons of the N-terminal glycyl residues. In 0.13 mM Ni(III)-peptide at p[H+] 10.3, this pathway accounts for 60% of the reaction. The cross-linked peptide is subject to oxidation via atmospheric O2, where the 2,3-diaminobutanedioic acid is converted to a 2,3-diaminobutenedioic acid. The products observed at

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Section: Resultssupporting

confidence: 92%

Oxidative Self-Decomposition of the Nickel(III) Complex of Glycylglycyl-l-histidylglycine

et al. 2004

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“…The triglycine, Gly-Gly-Ala and Gly-Ala-Gly, complexes of Ni(III) react with bpy, phen, en, and dien to form ternary complexes where the added ligands are chelated as it was seen from EPR spectra [244]. The complexes [Ni III (H Ϫ2 GlyGly-Ala)(H 2 O) 2 ] readily forms mixed-ligand complexes with en and dien.…”

Section: Nickel(iii) Peptide Complexesmentioning

confidence: 95%

“…This indicates a tridentate coordination of dien. Formation of Ni(III)-tripeptide axial donor species leads to complexes that are more stable than the parent Ni(III) complex with regard to redox decomposition in neutral and basic solutions [244].…”

Section: Nickel(iii) Peptide Complexesmentioning

confidence: 99%