Analytical Sciences

Determination of the Molar Extinction Coefficients of the B800 and B850 Absorption Bands in Light-harvesting Complexes 2 Derived from Three Purple Photosynthetic Bacteria Rhodoblastus acidophilus, Rhodobacter sphaeroides, and Phaeospirillum molischianum by Extraction of Bacteriochlorophyll a

Yoshitaka SAGA*,** and Keiya HIROTA*

*Department of Chemistry, Faculty of Science and Engineering, Kinki University, Higashi-Osaka, Osaka 577-8502, Japan
**PRESTO, Japan Science and Technology Agency, Kawaguchi, Saitama 332-0012, Japan

The molar extinction coefficients of light-harvesting complex 2 (LH2) have been ambiguous in spite of its fame and wide utilization. Herein we determine the molar extinction coefficients of the LH2 proteins derived from the three purple photosynthetic bacteria Rhodoblastus acidophilus, Rhodobacter sphaeroides and Phaeospirillum molischianum at 298 K by direct extraction of bacteriochlorophyll (BChl) a from the lyophilized proteins, followed by estimation of BChl a amounts from their electronic absorption spectra.

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