Frank Müh, J. Rautter, W. Lubitz,
"Effects of zwitterionic detergents on the primary donor of bacterial reaction centers"
, in WILEY-V C H VERLAG GMBH, in Berichte der Bunsen-Gesellschaft-Physical Chemistry Chemical Physics, Vol. 100, Nummer 12, 12-1996, ISSN: 0005-9021
Effects of zwitterionic detergents on the primary donor of bacterial reaction centers
Sprache des Titels:
The effects of zwitterionic detergents on the spectroscopic properties of the primary electron donor P of photosynthetic reaction centers (RCs) from the purple nonsulfur bacterium Rhodobacter sphaeroides are investigated. When RCs are solubilized with N-(n-alkyl)-N,N-dimethyl-3-ammonio-1-propanesulfonates (sulfobetaines) the maximum of the characteristic near-infrared absorption of P, lambda(max), is shifted to lower wavelengths at room temperature as compared with nonionic detergents. While the range of the blueshift (lambda(max) = 850-862 nm) is identical for different sulfobetaines, the dependence of the shift on the detergent/RC ratio varies systematically with the number of carbon atoms in the n-alkyl-chain. N-lauryl-N,N-dimethyl-amine-N-oxide (LDAO), a zwitterionic detergent with a less polar head group, is only able to induce blueshifts of lambda(max) down to 859 nm at much higher detergent/RC ratios. ENDOR experiments performed on the primary donor radical cation P-+. reveal that two distinct states of P exist in such samples. Thus the optical bandshifts are caused by transitions between two spectroscopic species, called P-866 and P-850. We interpret the detergent effect as an electrostatic influence of the detergent head groups on the equilibrium between two protein conformations which in turn affect the structure of the primary donor.
Sprache der Kurzfassung:
Berichte der Bunsen-Gesellschaft-Physical Chemistry Chemical Physics