Cytochrome c: electron emission, photodegradation and mutual interaction with vitamin C.
Cytochrome c (Cytc) in airfree, aqueous media (pH ~7.4; 37°C) can emit e(-)(aq) when exited in single state by monochromatic UV light (λ=254 nm). The obtained Qi(e(-)(aq)) at lower Cytc concentrations is higher compared to the amount obtained at higher substrate concentrations because at >10(-8) mol l(-1) Cytc 'associates' (unstable complexes) are formed, which consume a part of the ejected e(-)(aq). The primary, as well as secondary, photolytic products of the substrate likewise emit e(-)(aq), but with much lower Qi(e(-)(aq)) values. On the other hand, the photolysis Q(Cytc) values are lower than those of Qi(e(-)(aq)), since Cytc transients can be regenerated by partial consumption of emitted e(-)(aq). In addition to this, the produced Cytc(•+) (radical cations) can react with water, thus also regenerating Cytc.
University of Vienna, Faculty of Life Sciences, Section of Radiation Biology, Althanstr. 14, 1090 Vienna, Austria. nikola.getoff@univie.ac.at
Nikola
N
Getoff
Günter
G
Walder
D000465:Algorithms; D001205:Ascorbic Acid / Q000737:chemistry* / Q000378:metabolism; D045304:Cytochromes c / Q000737:chemistry* / Q000378:metabolism; D004583:Electrons; D006863:Hydrogen-Ion Concentration; D007700:Kinetics; D008956:Models, Chemical; D010084:Oxidation-Reduction / Q000528:radiation effects; D010782:Photolysis / Q000528:radiation effects; D011485:Protein Binding / Q000528:radiation effects; D012996:Solutions / Q000737:chemistry; D014466:Ultraviolet Rays; D014867:Water / Q000737:chemistry
D012996:Solutions; D014867:Water; D045304:Cytochromes c; D001205:Ascorbic Acid