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http://www.pnas.org/content/104/21/8749/F1.large.jpg
Vitamine c + zuurstof
> waterstofperoxide + zuurstof
De vitamine c onttrekt zuurstof aan ijzer(Fe), belangrijk voor zuurstoftransport, en wordt vervolgens omgezet in h2o2, en daarna nog eens in water en zuurstof onder invloed van catalase.
Quote:
Proposed mechanism of preferential formation of Asc•− and H2O2 in extracellular fluid compared with blood. After oral and parenteral administration, ascorbic acid is proposed to achieve equivalent concentrations in blood (left side) and extracellular fluid (right side). In extracellular fluid, pharmacologic concentrations of ascorbic acid lose one electron and form Asc•−. The electron reduces a protein-centered metal: An example reaction is shown as reduction of Fe3+ to Fe2+. Fe2+ donates an electron to oxygen, forming active oxygen including superoxide (O2 •−) with subsequent dismutation to H2O2 (17). In blood (left side), it is proposed that these reactions are damped or inhibited (dashed lines). Asc•− appearance will be inhibited by red blood cell membrane-reducing proteins (18) and/or by large plasma proteins that do not distribute to the extracellular space. Any formed H2O2 will be immediately destroyed by plasma catalase and red blood cell GSH peroxidase, so that no H2O2 will be detectable (14–16). The identities of the metal-centered proteins are unknown.