ESR study of the non-enzymic scission of xyloglucan by an ascorbate-H2O2-copper system: the involvement of the hydroxyl radical and the degradation of ascorbate
Xyloglucan is degraded by a mixture of copper(II), hydrogen peroxide and ascorbate. In the presence of ascorbate and/or hydrogen peroxide, copper(II) species were rapidly reduced to copper(I), which react with hydrogen peroxide. Spin-trapping experiments showed that hydroxyl radicals formed and atta...
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Veröffentlicht in: | Journal of inorganic biochemistry 2001-04, Vol.84 (3-4), p.179-187 |
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Format: | Artikel |
Sprache: | eng |
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Zusammenfassung: | Xyloglucan is degraded by a mixture of copper(II), hydrogen peroxide and ascorbate. In the presence of ascorbate and/or hydrogen peroxide, copper(II) species were rapidly reduced to copper(I), which react with hydrogen peroxide. Spin-trapping experiments showed that hydroxyl radicals formed and attacked xyloglucan causing its degradation. The formation of a carbon-centred ascorbyl (C-ascorbyl) radical and its degradation with the formation of oxalate, was also caused by hydroxyl radicals. As a consequence, the features of the bis(oxalate) copper(II) complex clearly appeared in the frozen solution ESR spectra. The formation of carbon-centred radicals on the xyloglucan is the trigger for a series of possible molecular rearrangements which led to its oxidative scission. |
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ISSN: | 0162-0134 |
DOI: | 10.1016/S0162-0134(00)00235-X |