Free radicals induced peptide damage in the presence of transition metal ions: A plausible pathway for biological deleterious processes

Sara Goldstein, Gidon Czapski, Haim Cohen, Dan Meyerstein

Research output: Contribution to journalArticlepeer-review

17 Scopus citations

Abstract

When aqueons N2O-saturated solutions containing glycine-N-tert-butylamide (L) and Cr2+(aq) or Cu+(aq) are irradiated, transients with metal-carbon σ-bonds are formed with rate constants of (4.4 ± 0.5) × 107 and (5.2 ± 0.3) × 109 M- s-, respectively. In the chromium(II) system, after a fast process (k = 43 ± 4 s-1), possibly chelaton, the transient decomposes verly slowly (k = 0.003 ± 0.001 h-1) via a β-elimination process to yield 2-methylpropene and glycinamide, i.e., a cleavage of the peptide bond takes place. However, in the copper(I) system the heterolytic cleavage of the σ-bond and the reaction of the transient complex with L-Cu2+ compete efficiently with the β-elimination process. The latter reaction leads to some modification of the amide. We suggest that the formation and decomposition od transients with metal-carbon σ-bonds may be describe an additional pathway for peptide damage induced by alipathic free radical precursors (e.g., OH., H2O2) in the presence of transition metal ions.

Original languageEnglish
Pages (from-to)11-18
Number of pages8
JournalFree Radical Biology and Medicine
Volume17
Issue number1
DOIs
StatePublished - 1 Jan 1994

Keywords

  • Cr(aq)
  • Cu(aq)
  • Free radicals
  • Metal-carbon σ-bond
  • Peptide damage
  • Pulse radiolysis
  • β-elimination

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