The role of water on photochemical activities of membrane protein complexes of bacteria

Cells of purple bacteria (Rhodospirillum rubrum) transferred into HTS (Hexa ne, Tween and Span)- reverse micelles displayed the primary photochemical r eactions of photosynthesis measured as fast bacterichlorophyll (BChl) fluor escence induction kinetics and photooxidation of P800 (measured as light in duced absorption changes at 820 nm). The cells in MTS-reverse micelles show ed water dependent increases in Variable fluorescence for extended periods of time. Cells in MTS-reverse micelles without water totally lost the varia ble fluorescence after 24 h, while in the presence of 6% water they behaved almost like the normal cells maintaining their activity even after 24 hr. H-1-Nuclear-Magnetic-Resonance (IH-NMR) studies shows that the bound/free w ater ratio decreased with increasing concentration of water in MTS-reverse micelles. The obtained results, altogether, clearly demonstrate that the am ount and physical state of water determine the primary photosynthetic activ ity of bacteria in MTS-reverse micelles.