Carotenoid stoichiometry in the LH2 crystal: no spectral evidence for the presence of the second molecule in the alpha/beta-apoprotein dimer.
In this work we have investigated the carotenoid-protein interactions in LH2 complexes of Rhodopseudomonas acidophila both in "free in solution" mixed-micelles and in three-dimensional crystals by Raman spectroscopy in resonance with the carotenoid (Car) molecules. We show that the Car molecules when bound to their binding pockets show no significant differences when the complexes are "free in solution" or packed in crystalline arrays. Furthermore, there is no significant wavelength dependence in the Raman spectrum of the Car molecules of LH2. This indicates that there is only one Car configuration in LH2 and thus only one molecule per alpha/beta-heterodimer.
Gall
Andrew
A
Service de Biophysique des Fonctions Membranaires, Département de Biologie Joliot Curie/CEA et URA CNRS 2096, CEA Saclay, 91191 Gif-sur-Yvette Cedex, France. andrew.gall@cea.fr
Gardiner
Alastair T
AT
Cogdell
Richard J
RJ
Robert
Bruno
B
D001059:Apoproteins / Q000737:chemistry*; D001426:Bacterial Proteins / Q000737:chemistry*; D002338:Carotenoids / Q000737:chemistry*; D003460:Crystallization; D019281:Dimerization; D045342:Light-Harvesting Protein Complexes / Q000737:chemistry*; D012241:Rhodopseudomonas / Q000737:chemistry*; D013059:Spectrum Analysis, Raman; D013696:Temperature
D001059:Apoproteins; C081521:B800-850 light-harvesting complex, bacteria; D001426:Bacterial Proteins; D045342:Light-Harvesting Protein Complexes; D002338:Carotenoids