Unusual twinning in an acetyl coenzyme A synthetase (ADP-forming) from Pyrococcus furiosus

A recombinant form of an acetyl coenzyme A synthetase (ADP-forming) from Pyrococcus furiosus has been crystallized. Crystallization was accomplished by the sitting-drop vapour-diffusion technique. Crystals belong to the monoclinic space group C2, with unit-cell parameters a = 131.3, b = 186.1, c = 121.5 Å, β = 122.6°, and diffract to 2.0 Å resolution on a synchrotron-radiation source. The unit-cell parameters allow twinning to the higher apparent space-group symmetry F222 by twin-lattice quasi-symmetry. The twinning fraction for the data is close to 40%. Two other data sets in the PDB show similar twinning.