Photobleaching of the resonance Raman lines of cytochromes in living yeast cells

• Green light leads to the photobleaching of the cytochrome Raman lines.
• The cytochrome photobleaching is local and recoverable at low exposition.
• The power dependence of photobleaching rate is described by quadratic function plus a constant.
• The photobleaching rate can provide information about dark redox balance rates.

The photobleaching of the resonance cytochrome Raman lines in living Saccharomyces cerevisiae cells was studied. The photobleaching rate versus the irradiation power was described by square function plus a constant in contrast to the linear dependence of the photoinjury rate. This difference distinguishes the cytochrome photooxidation from other processes of the cell photodamage. The square dependence is associated with the reaction involving two photogenerated intermediates while the constant with the dark redox balance rates. This work demonstrates a potential of Raman spectroscopy to characterize the native cytochrome reaction rates and to study the cell photodamage precursors.

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