Crystallization of recombinant human interleukin 1β

Abstract The gene for the fully processed form of human interleukin 1β was cloned from SK-hep-1 hepatoma cellular RNA and expressed at high levels in E. coli . The protein produced in E. coli . was purified to homogeneity by standard chromatographic methods, including adsorption and desorption from Procion Red Sepharose, sizing on a Superose 12 FPLC column, and anion exchange chromatography on QAE Sepharose. The result is a biologically active protein, rIL-1β, that migrates on two-dimensional gels as a single spot with a pI of 6.5 ± 0.2 and a molecular mass of 17, 500 daltons. Crystals of rIL-1β have been produced from concentrated solutions of the protein by ammonium sulfate precipitation. The crystals are tetragonal, have space group P4 1 or its enantiomer, have lattice constants of a = 58.46(1) A and c = 77.02(3) A, and scatter to at least 2 A resolution. A structure determination ba these crystals is underway.