Cytochrome c: Electron Emission, Photodegradation and Mutual Interaction with Vitamin C

Cytochrome c (Cytc) in airfree, aqueous media (pH similar to 7.4; 37 degrees C) can emit e(aq)(-) when exited in single state by monochromatic UV light (lambda=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(-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(center dot+) (radical cations) can react with water, thus also regenerating Cytc.