Crystallization of the reaction center from Rhodobacter sphaeroides in a new tetragonal form.

The reaction center from the nonsulfur purple bacterium Rhodobacter sphaeroides has been crystallized in a new form. The crystals grew in the presence of polyethylene glycol 4000, the detergent beta-octyl glucoside, and the amphiphiles heptane triol and benzamidine hydrochloride, using the sitting drop method. The space group of these crystals is tetragonal, P4(1)(4(3))2(1)2, and the cell constants area a = b = 141.5 A and c = 276.7 A with probably 2 proteins per asymmetric unit. A native data set has been set collected to a resolution of 2.8 A consisting of 56,332 unique reflections (50,731 with F > 2 sigma) with an Rsym of 9.5%. Analysis of the diffraction data is underway using molecular and isomorphous replacement.