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A Spectroscopic Study of a Photosystem I Antenna Complex

  • Ishita Mukerji
  • Kenneth Sauer

Abstract

The unusual long wavelength fluorescent behavior of Photosystem I (PSI) has been well documented (1) This study investigates the origin and temperature dependence of this emission using an intact peripheral antenna preparation isolated from a PSI complex originally extracted from spinach. This antenna complex (LHCP-I) contains polypeptides in the 19–24 kDa range and exhibits a red shift in emission maximum from 685nm (F685) to 735nm (F735) as the temperature is lowered. Fluorescence excitation spectra demonstrate that chlorophyll b (chl b) preferentially stimulates the long wavelength emission at both room temperature and 77K and also indicate the presence of a long wavelength absorber in the 703–708nm range. Excitation polarization scans show a rising polarization value reaching a maximum of 0.3 from 705nm to 725nm, confirming the presence of a long wavelength pigment or pigments which are primarily responsible for emission at 735nm (F735). Absorption spectra demonstrate that this species comprises a small percentage of the total pigment population in the light harvesting antenna. The overall fluorescence yield of the complex increases as the temperature is lowered suggesting the presence of a quenching mechanism which does not involve the reaction center, P700.

Keywords

Reaction Center Excitation Spectrum Fluorescence Yield Antenna Complex Fluorescence Excitation Spectrum 
These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

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Copyright information

© Springer Science+Business Media New York 1990

Authors and Affiliations

  • Ishita Mukerji
    • 1
  • Kenneth Sauer
    • 1
  1. 1.Department of Chemistry and Chemical Biodynamics Division, Lawrence Berkeley LaboratoryUniversity of CaliforniaBerkeleyUSA

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