Linear dichroism of electric field oriented bacteriochlorophyll a-protein from green photosynthetic bacteria

William B. Whitten, Robert M. Pearlstein, Edwin F. Phares, Nicholas E. Geacintov

Research output: Contribution to journalArticle

Abstract

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.

Original languageEnglish (US)
Pages (from-to)491-498
Number of pages8
JournalBBA - Bioenergetics
Volume503
Issue number3
DOIs
StatePublished - Sep 7 1978

ASJC Scopus subject areas

  • Biophysics
  • Biochemistry
  • Cell Biology

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