CHARACTERIZATION OF PHOTOSYNTHETIC REACTION CENTERS FROM RHODOBACTER-SPHAEROIDES AT THE AIR-WATER-INTERFACE AND IN LANGMUIR-BLODGETT-FILMS

Monolayers of the reaction center complex from Rhodobacter sphaeroides were prepared from dodecyl beta-maltoside suspensions at an air-water interface. The stability of these monolayers was determined A value o f 28 nm(2) per complex was obtained for the cross-sectional area from the equilibrium surface pressure-area isotherms. Multilayer films of a lternating arachidic acid-reaction center monolayers were constructed on quartz slides by the Langmuir-Blodgett technique. Absorption spectr oscopy was used to confirm the structural integrity of the complex and to determine the transfer ratio. Low-angle X-ray diffraction measurem ents were performed on these multilayers. A value of 64 Angstrom was o btained for the thickness of the reaction center monolayer in the mult ilayer film. This novel approach can be used to study multilayers of o ther membrane-bound proteins.