Ethylenediammine is not detrimental to the photoactivity of the bacterial photosynthetic reaction center

The effect of the exposure of the photosynthetic reaction center from the purple bacterium Rhodobacter sphaeroides to ethylenediamine (EDA) was investigated by transient absorption spectroscopy and UV-Visible-Near Infrared absorption spectroscopy. We show that EDA is not detrimental to the photoactivity of the protein even at pH close to 12. EDA instead appears to inhibit the secondary quinone binding site with an apparent binding constant of 19.05 mM(-1).