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Free radicals in primary photobiological processes
1Russian State Medical University, Moscow. avlad@iki.rssi.ru
Membrane & Cell Biology
|June 24, 1999
Summary
Free radicals are the initial products in photochemical reactions of proteins and chlorophyll systems. Their recombination releases photons, explaining chemiluminescence properties and low quantum yields in these systems.
Area of Science:
- Photochemistry
- Biophysics
- Free Radical Chemistry
Background:
- The discovery of semiquinone free radicals in chlorophyll photoreduction by Krasnovsky in 1953.
- Free radicals play a crucial role in various photochemical processes.
Purpose of the Study:
- To review findings on free radical participation in UV-irradiated aromatic amino acids, proteins, and lipids.
- To examine free radical involvement in chemiluminescence (CL) of protein and chlorophyll systems.
Main Methods:
- Analysis of photochemical reactions under UV irradiation.
- Investigation of chemiluminescence in biological systems.
- Molecular energetics analysis of electronic transitions.
Main Results:
- Free radicals are consistently the primary products in studied photochemical reactions.
- Radical recombination reactions are accompanied by photon emission (chemiluminescence).
- Molecular energetics favor radiationless transitions, explaining low CL quantum yields and spectral properties.
Conclusions:
- Free radicals are fundamental to the studied photochemical and chemiluminescence reactions.
- The energetic pathways of radical recombination dictate the observed chemiluminescence characteristics.
- The findings provide insights into the mechanisms of light emission in biological molecules.