MIXED LIPID-PROTEIN FILMS OF BACTERIAL PH OTOSYNTHETIC REACTION CENTERS .2. INVESTIGATION OF MIXED MULTILAYERS ONTO SOLID SUPPORTS

Mixed lipid-protein multilayers composed of the reaction center (RC) p roteins from the Chloroflexus aurantiacus and Rhodobacter sphaeroides (wild type) photosynthetic bacteria and synthetic lipids were investig ated. The optimal conditions for forming thin films on solid plates (a ppr. 100% transfer) were 30 mN/m surface pressure and transfer of the interfacial monolayers from the buffer/air interface onto the plates b y the Langmuir-Schaefer method. The films transferred onto quartz and optical transparent current-conducting plates retained their optical a nd photoelectric properties. The preferential orientation of the prote in on the interfacial surface depended on the type of lipid used. In R C-acryloylphosphatidylethanolamine films, the H-subunit of the RCs fro m Rhodobacter, sphaeroides was oriented toward the water phase, in con trast to RC-diacetylene acid films, in which the H-subunit was oriente d toward the air phase. It is shown that RCs can change their orientat ion in a monolayer, even to the opposite one, depending on the type of lipid matrix.