title: Crystallization of succinyl-CoA synthetase from Escherichia coli.
abstract: Well formed, tetragonal prisms of succinyl-CoA synthetase from Escherichia coli have been crystallized at room temperature from ammonium sulfate and mixtures of sodium and potassium phosphates. A systematic survey of the conditions for crystallization of the enzyme has been carried out. This has shown the addition of a small amount of an organic solvent (acetone, 2-methyl-2,4-pentanediol, tert-butyl alcohol, or tertamyl alcohol) to the phosphate media and of CoA to the sulfate media to be beneficial in producing large, single crystals suitable for analysis by x-ray diffraction methods. Preliminary examination of precession photographs reveals that the crystals from phosphate media have a unit cell of symmetry P4222 with dimensions a = b = 94 A and c = 248 A. Evidence suggests that there may be only half of the (alpha beta)2 tetramer/asymmetric unit in these crystals. The crystals from ammonium sulfate media have unit cell dimensions of a = b = 99 A and c = 399 A, a space group of P4122 (P4322), and one tetramer/asymmetric unit. They diffract to a resolution of 3.4 A. Both crystal types have large solvent contents of about 65% of the unit cell volumes. A parameter called "quality index" is introduced to facilitate comparison of crystals grown under a variety of conditions with respect to their quality of x-ray diffraction.
mesh_terms: D003065:Coenzyme A / Q000378:metabolism; D003066:Coenzyme A Ligases / Q000302:isolation & purification*; D003460:Crystallization; D004926:Escherichia coli / Q000201:enzymology*; D046911:Macromolecular Substances; D011487:Protein Conformation; D012997:Solvents; D013389:Succinate-CoA Ligases / Q000302:isolation & purification* / Q000378:metabolism; D014961:X-Ray Diffraction
chemical_list: D046911:Macromolecular Substances; D012997:Solvents; D003066:Coenzyme A Ligases; D013389:Succinate-CoA Ligases; D003065:Coenzyme A