Crystallization and preliminary X-ray analysis of the monomeric Cu,Zn superoxide dismutase from Escherichia coli

The Cu,Zn superoxide dismutase (Cu,Zn SOD) originally isolated from the periplasmic space of Escherichia coli has been cloned and overexpressed in the E. coli strain BMH 71/18. The protein has been purified as a single component of 17,000 Da, corresponding to one subunit of the common dimeric eukaryotic Cu,Zn SODs. Large crystals of the purified protein have been grown in the presence of polyethylene glycol 4,000 at pH 8.5; the crystals belong to the monoclinic space group P2(1), with unit cell constants a = 33.1 Angstrom, b = 52.6 Angstrom, c = 43.3 Angstrom, beta = 111.4 degrees. One SOD subunit is contained in the asymmetric unit, yielding a V-m value of 2.1 Angstrom(3)/Da; the crystals diffract X-rays beyond 2.0 Angstrom resolution.