Spectroscopy and structure of bacteriochlorophyll dimers. I. Structural consequences of nonconservative circular dichroism spectra.
The origin of the nonconservative nature of the circular dichroism (CD) spectrum of bacteriochlorophyll dimers is investigated. It is shown that coupling between the Qy and Qx transitions can, under rather restricting circumstances, lead to an asymmetrical CD spectrum: only for a limited set of relative orientations of the monomers within the dimer is the spectrum found to be asymmetrical. The relation between intensity and asymmetry of the CD spectrum is elucidated. The results are applied to the B820 subunit of the LH1 antenna system and subsequently to the antenna system LH1 itself. Differences in the geometry of the BChls in LH1 versus the LH2 structure are discussed.
Koolhaas
M H
MH
Department of Theoretical and Physical Chemistry, Vrije Universiteit, Amsterdam, The Netherlands. koolhaas@chem.vu.nl
van der Zwan
G
G
van Mourik
F
F
van Grondelle
R
R
D001426:Bacterial Proteins; D001429:Bacteriochlorophylls / Q000737:chemistry*; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002942:Circular Dichroism; D019281:Dimerization; D045342:Light-Harvesting Protein Complexes; D015394:Molecular Structure; D045322:Photosynthetic Reaction Center Complex Proteins / Q000737:chemistry; D011487:Protein Conformation; D012247:Rhodospirillum rubrum / Q000737:chemistry / Q000378:metabolism; D013053:Spectrophotometry
D001426:Bacterial Proteins; D001429:Bacteriochlorophylls; D045342:Light-Harvesting Protein Complexes; D045322:Photosynthetic Reaction Center Complex Proteins; C094744:light-harvesting complex 1, Rhodospirillum