Crystallization and preliminary crystallographic analysis of 3-carboxy-cis,cis-muconate lactonizing enzyme from Neurospora crassa

Crystals of 3-carboxy-cis,cis-muconate lactonizing enzyme (CMLE; E.C. 5.5.1.5) from Neurospora crassa that diffract to high resolution have been obtained. The crystals belong to the orthorhombic space group P2₁2₁2₁ with unit-cell dimensions a = 92.1, b = 159.7, c = 236.6 Å (at 103 K) and diffract at most to 2 Å resolution. The asymmetric unit of the crystals appears to contain two tetrameric CMLE molecules making up a total of 328 kDa per asymmetric unit. Both cross-linking with glutaraldehyde and cryo-cooling to 103 K have been used to facilitate data collection because the crystals are unstable in the X-ray beam; both techniques extend the crystal lifetime but cryo-cooling, unlike glutaraldehyde cross-linking, does not lower the quality of the diffraction pattern.