RESUMO
The antenna complexes from Rps. cryptolactis have been isolated and purified. Rps. cryptolactis contains two types of variable antenna complex, B800-850 and B800-820 as well as the 'core' B875 antenna complex. The variable antenna complexes contain more than two types of antenna apoprotein, and have a Bchla:carotenoid ratio of â¼2:1. They can both be crystallised, but the B800-820 complex is the easiest with which to get relatively large single 3-D crystals (up to 0.5 mm in each dimension).
RESUMO
Large single crystals (up to 1 mm in each dimension) of the B800-850 antenna complex from Rhodopseudomonas acidophila strain 10050 have been grown in the presence of beta-octyl-glucoside. These crystals have the space group R32 and unit cell dimensions of a = b = 119.9 A and c = 297.0 A. Recently we have improved our crystallization procedures so that all crystals now diffract reliably to beyond 3.5 A, with some diffracting to below 3 A. A range of isomorphous heavy atom derivatives have been prepared and we are now engaged in locating the heavy atom sites within the unit cell.
Assuntos
Proteínas de Bactérias/química , Rodopseudomonas/química , Apoproteínas/química , Proteínas de Bactérias/isolamento & purificação , Bacterioclorofilas/química , Cristalização , Difração de Raios XRESUMO
The B800-820 light-harvesting complex, an integral membrane protein, from Rhodopseudomonas acidophila strain 7750 has been crystallized. The tabular plates have a hexagonal unit cell of a = b = 121.8 A and c = 283.1 A and belong to the space group R32. X-ray diffraction data have been collected to 6 A resolution, using an area detector on a rotating anode source. The B800-820 light-harvesting complex is comprised of four low molecular weight apoproteins (B800-820 alpha 1, B800-820 alpha 2, B800-820 beta 1 and B800-820 beta 2). Polyacrylamide gel electrophoresis shows that the complex exists as an oligomeric assembly, with an apparent molecular weight of 92,000.
