Discovery of Natural Photosynthesis using Zn-Containing Bacteriochlorophyll in an Aerobic Bacterium Acidiphilium rubrum

N. Wakao, N. Yokoi, N. Isoyama, A. Hiraishi, K. Shimada, M. Kobayashi, H. Kise, M. Iwaki, S. Itoh, S. Takaichi
1996 Plant and Cell Physiology  
We discovered natural photosynthesis using Zn-containing bacteriochlorophyll a in an acidophilic bacterium Addiphilium rubrum. Chemical analysis of the cell extracts gave a 13 : 2 :1 molar ratio of Zn-bacteriochlorophyll a : Mg-bacteriochlorophyll a : bacteriopheophytin a. Most of the pigments are associated with fully active reaction center and light-harvesting complexes analogous to those in purple photosynthetic bacteria. The finding indicates an unexpectedly wide variability of
more » ... s. Photosynthesis has been converting solar energy to chemical energy since its evolution on the early Earth, by use of the functions of Mg-containing porphyrin derivatives, namely, chlorophylls. The appropriate oxidation-reduction potentials and long-lived excited states of chlorophylls are favorable for the electron transfer reactions and the light-harvesting. These may be the reason for the photosynthetic organisms to choose chlorophylls among others. Among the chlorophyll derivatives containing metals other than Mg, only Zn-containing chlorophylls have chemical features comparable to Mg-chlorophylls (Watanabe and Kobayashi 1991). Zn-porphyrin derivatives are usually more stable than Mg-derivatives, and have been widely used in the studies of artificial photosynthesis (Wasielewski and Niemczyk 1984, Osuka et al. 1993). Zn-containing bac-Abbreviations: BChl, bacteriochlorophyll a; BPhe, bacteriopheophytin a.
doi:10.1093/oxfordjournals.pcp.a029029 fatcat:qxj6c654obgrlktz6srvsabsgi