Dipole-dipole transfer between acetone solvates of chlorophyll a and chlorophyll a dihydrate dimers in water/acetone mixtures. A model for P680 sensitized excitation
✍ Scribed by Angela Agostiano; Karen A. Butcher; Michael S. Showell; Albert J. Gotch; Francis K. Fong
- Publisher
- Elsevier Science
- Year
- 1987
- Tongue
- English
- Weight
- 384 KB
- Volume
- 137
- Category
- Article
- ISSN
- 0009-2614
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✦ Synopsis
We describe a simple model for P680 sensitized excitation in photosynthesis. Chl a fluorescence quenching effects observed when water is added to Chl a solutions in acetone are shown to be the result of resonant transfer between acetone solvates of monomeric Chl a, Chl aAc, and dimers of Chl a dihydrate. The presence of (Chl a.2H,0)2 is evidenced by a 678 nm difference absorbance-(M) band obtained on conversion of a 680 nm absorption shoulder to polycrystalline Chl a precipitate, (Chl a.zH,O),. The equilibration between (Chl a,2H,O)* and Chl a.Ac as a principal mechanism for Chl a.Ac fluorescence quenching is supported by theoretical fits of the data.