TY - JOUR
T1 - Linear dichroism of electric field oriented bacteriochlorophyll a-protein from green photosynthetic bacteria
AU - Whitten, William B.
AU - Pearlstein, Robert M.
AU - Phares, Edwin F.
AU - Geacintov, Nicholas E.
N1 - Funding Information:
This research was sponsored by the U.S. Energy Research and Development Administration under contract with the Union Carbide Corporation. We are g~ateful to J.M. Olson for providing an inoculum of P. aestuariia nd for much helpful advice on culturing the organism and purifying the Bchl a-protein. We also wish to thank N. Rigopoulos for advice and M.V. Long for expert technical assistance. In addition, we thank F.A. Modine for taking the CD spectra, and W.A. Arnold and J.R. Azzi for furnishing the chloroplasts.
PY - 1978/9/7
Y1 - 1978/9/7
N2 - Bacteriochlorophyll a-protein from Prosthecochloris aestuarii strain 2K was oriented in a pulsed electric field. The room temperature linear dichroism spectrum of the oriented protein in the Qy region of the bacteriochlorophyll a absorption exhibits a single asymmetrical peak at 813 nm with a shoulder extending to the blue. The ≈12 nm fullwidth of the linear dichroism peak is only about half that of the 300 K absorption spectrum. The linear dichroism at 813 nm was not saturated at field strengths of up to 15 kV/cm. The time dependence of the linear dichroism suggests that the orienting particles are aggregates of at least some tens of bacteriochlorophyll a-protein trimers. The linear dichroism peak coincides in wavelength with the 813-nm peak of the 300 K, 4th derivative absorption spectrum of the protein and is therefore attributed to the bacteriochlorophyll a Qy exciton transition observed in absorption at the same wavelength.
AB - Bacteriochlorophyll a-protein from Prosthecochloris aestuarii strain 2K was oriented in a pulsed electric field. The room temperature linear dichroism spectrum of the oriented protein in the Qy region of the bacteriochlorophyll a absorption exhibits a single asymmetrical peak at 813 nm with a shoulder extending to the blue. The ≈12 nm fullwidth of the linear dichroism peak is only about half that of the 300 K absorption spectrum. The linear dichroism at 813 nm was not saturated at field strengths of up to 15 kV/cm. The time dependence of the linear dichroism suggests that the orienting particles are aggregates of at least some tens of bacteriochlorophyll a-protein trimers. The linear dichroism peak coincides in wavelength with the 813-nm peak of the 300 K, 4th derivative absorption spectrum of the protein and is therefore attributed to the bacteriochlorophyll a Qy exciton transition observed in absorption at the same wavelength.
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U2 - 10.1016/0005-2728(78)90148-2
DO - 10.1016/0005-2728(78)90148-2
M3 - Article
C2 - 687613
AN - SCOPUS:0018127276
VL - 503
SP - 491
EP - 498
JO - Biochimica et Biophysica Acta - Bioenergetics
JF - Biochimica et Biophysica Acta - Bioenergetics
SN - 0005-2728
IS - 3
ER -