Langmuir-Blodgett monolayer films of bacterial photosynthetic membranes and isolated reaction centers: preparation, spectrophotometric and electrochemical characterization.

The Langmuir-Blodgett (LB) film technique has been successfully applied to the construction of stable and photo-active films of chromatophore membranes and isolated reaction centers from two species of photosynthetic bacteria, Rhodobacter sphaeroides and Rhodopseudomonas viridis. LB films of these preparations were characterized at the air/water interface through compression isotherms and film stabilities. Films deposited on glass slides were analyzed by spectrophotometric and redox potentiometric techniques. The results obtained indicate that the in vivo properties of the photosynthetic apparatus in the deposited films are essentially unchanged. Furthermore, the pigments and redox cofactors in the films are highly oriented and offer a unique opportunity for structural and functional studies of the kind described in the accompanying paper (Biochim. Biophys. Acta 1057 (1991) 258-272).