Tetrapyrrol Derivatives Shown by Fluorescence Emission and Excitation Spectroscopy in Cells of Rhodopseudomonas capsulata Adapting to Phototrophic Conditions

Bacteriochlorophyll Complexes, Precursors, Tetrapyrrols, Rhodopseudomonas capsulata, Photosynthetic Apparatus Aerobically in the dark grown cells were incubated semiaerobically (30 min) and afterwards 180 min anaerobically in the light During phototrophic induction the bacteriochlorophyll concentra­ tion increased from 0.26 to 2 . 1 0 nmol/mg cell protein. In samples taken at different times after lowering of oxygen partial pressure the following tetrapyrrol derivatives were identified by fluorescence emission and excitation spectroscopy at 1.7 K: Mg-protoporphyrin EX-monomethylester, Mg-2,4-divinylphaeoporphyrin a5-monomethylester, 2-devinyl-2 -hydroxyethyl-chlorophyllide, 2 -devinyl-2 -hydroxyethyl-pheophorbide, chlorophyllide a, pheophorbide, bacteriopheophorbide, bacteriopheophytin, bacteriochlorophyllide and bacte­ riochlorophyll a in different pigment complexes. The highest relative concentrations of bacte­ riochlorophyll precursors normalized to the total amount of bacteriochlorophyll a were found in cells during the first hour of adaptation at 0.5 ^g Bchl/mg cell protein or less.