Crystallization of phycoerythrin 545 of Rhodomonas lens using detergents and unusual additives.
Phycoerythrin 545 from the cryptomonad alga, Rhodomonas lens, has been crystallized under a wide variety of conditions. Although this type of photosynthetic light-harvesting protein is water soluble, detergents were always required for crystallization. The crystals were typically poorly ordered, or ordered in only two dimensions. However, crystals that were well-ordered in three dimensions could be obtained under two different conditions. Both used polyethylene glycol as precipitant and the detergent lauryldimethylaminoxide, but the additives that were critical for obtaining well-ordered crystals were propionamide in one case and Cs+/Br- in the other. Crystals obtained in the presence of propionamide have the space group P2(1)2(1)2(1), with cell constants of a = 85.6 angstroms, b = 108.2 angstroms, and c = 131.0 angstroms, and contain two dimers [i.e., 2 x (alpha2beta2)] in the asymmetric unit. They show diffraction to at least 3.0 angstroms resolution. The crystals grown with Cs+/Br- are nearly isomorphous. Both types of crystals show intense, strongly polarized fluorescence, suggesting that energy transfer in the crystals is highly efficient. This should provide a basis for quantitative investigation of the role of exciton interactions in energy transfer in cryptomonad phycobiliproteins.
Becker
M
M
Abteilung für Strukturforschung, Max-Planck-Institut für Biochemie, Martinsried, Germany. becker@vr1.bio.bnl.gov
Stubbs
M T
MT
Huber
R
R
D002021:Buffers; D003460:Crystallization; D018360:Crystallography, X-Ray; D003902:Detergents; D056890:Eukaryota / Q000737:chemistry*; D010799:Phycoerythrin
D002021:Buffers; D003902:Detergents; C045714:phycoerythrin 545; D010799:Phycoerythrin