Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems: random attack or site-specific damage?

TY - JOUR

T1 - Oxidative damage to collagen and related substrates by metal ion/hydrogen peroxide systems

T2 - random attack or site-specific damage?

AU - Hawkins, C L

AU - Davies, Michael Jonathan

PY - 1997/2/27

Y1 - 1997/2/27

N2 - Degradation of collagen by oxidant species may play an important role in the progression of rheumatoid arthritis. Whilst the overall effects of this process are reasonably well defined, little is known about the sites of attack, the nature of the intermediates, or the mechanism(s) of degradation. In this study electron paramagnetic resonance spectroscopy with spin trapping has been used to identify radicals formed on collagen and related materials by metal ion-H2O2 mixtures. Attack of the hydroxyl radical, from a Fe(II)-H2O2 redox couple, on collagen peptides gave signals from both side chain (.CHR'R"), and alpha-carbon[.C(R)(NH-)CO-,R = side-chain]radicals. Reaction with collagen gave both broad anisotropic signals, from high-molecular-weight protein-derived radicals, and isotropic signals from mobile species. The latter may be low-molecular-weight fragments, or mobile side-chain species; these signals are similar to those from the alpha-carbon site of peptides and the side-chain of lysine. Enzymatic digestion of the large, protein-derived, species releases similar low-molecular-weight adducts. The metal ion employed has a dramatic effect on the species observed. With Cu(I)-H2O2 or Cu(II)-H2O2 instead of Fe(II)-H2O2, evidence has been obtained for: i) altered sites of attack and fragmentation, ii) C-terminal decarboxylation, and iii) hydrogen abstraction at N-terminal alpha-carbon sites. This altered behaviour is believed to be due to the binding of copper ions to some substrates and hence site-specific damage. This has been confirmed in some cases by electron paramagnetic resonance studies of the Cu(II) ions.

AB - Degradation of collagen by oxidant species may play an important role in the progression of rheumatoid arthritis. Whilst the overall effects of this process are reasonably well defined, little is known about the sites of attack, the nature of the intermediates, or the mechanism(s) of degradation. In this study electron paramagnetic resonance spectroscopy with spin trapping has been used to identify radicals formed on collagen and related materials by metal ion-H2O2 mixtures. Attack of the hydroxyl radical, from a Fe(II)-H2O2 redox couple, on collagen peptides gave signals from both side chain (.CHR'R"), and alpha-carbon[.C(R)(NH-)CO-,R = side-chain]radicals. Reaction with collagen gave both broad anisotropic signals, from high-molecular-weight protein-derived radicals, and isotropic signals from mobile species. The latter may be low-molecular-weight fragments, or mobile side-chain species; these signals are similar to those from the alpha-carbon site of peptides and the side-chain of lysine. Enzymatic digestion of the large, protein-derived, species releases similar low-molecular-weight adducts. The metal ion employed has a dramatic effect on the species observed. With Cu(I)-H2O2 or Cu(II)-H2O2 instead of Fe(II)-H2O2, evidence has been obtained for: i) altered sites of attack and fragmentation, ii) C-terminal decarboxylation, and iii) hydrogen abstraction at N-terminal alpha-carbon sites. This altered behaviour is believed to be due to the binding of copper ions to some substrates and hence site-specific damage. This has been confirmed in some cases by electron paramagnetic resonance studies of the Cu(II) ions.

KW - Amino Acids

KW - Ascorbic Acid

KW - Benzenesulfonates

KW - Collagen

KW - Collagenases

KW - Copper

KW - Electron Spin Resonance Spectroscopy

KW - Hydrogen Peroxide

KW - Hydroxyl Radical

KW - Iron

KW - Metals

KW - Nitroso Compounds

KW - Oxidants

KW - Oxidation-Reduction

KW - Peptides

KW - Phenylhydrazines

KW - Protein Binding

KW - Spin Trapping

M3 - Journal article

C2 - 9061043

SN - 0304-419X

VL - 1360

SP - 84

EP - 96

JO - Biochimica et Biophysica Acta - Reviews on Cancer

JF - Biochimica et Biophysica Acta - Reviews on Cancer

IS - 1

ER -