Abstract
Acaryochloris marina is a newly discovered and Chl d-dominated photosynthetic prokaryote. The absorption maximum of Chl d in organic solvents is located at wavelengths longer than that of Chl a by about 30 nm. In this study, the reversible absorption changes of Chl d by oxidation-reduction were investigated.
Chls were purified by column chromatography, and dissolved in aqueous micelles or MeOH. Reduction and oxidation was performed by adding dithionite or NaBH4 and ferricyanide, respectively.
The absorption maximum of reduced Chl d was blue-shifted by 40nm as compared with Chl d, and came back to the original position by oxidation. We determined a molecular structure of the reduced Chl d by MS spectroscopy to be 3-hydroxymethyl-Chl a. On the contrary, Chl a and b did not show a reversible change, indicating that electronic properties of Chl d are different from those of Chl a or Chl b.
