Different conformation of purified human recombinant interleukin 1 beta from Escherichia coli and Saccharomyces cerevisiae is related to different level of biological activity.

Human recombinant interleukin 1 beta produced in Escherichia coli and in Saccharomyces cerevisiae was purified to homogeneity by a combination of ion exchange, gel filtration and hydroxylapatite column chromatography. The two proteins, both expressed in the mature form, differ in that the protein secreted from yeast is glycosylated and lacks the first four amino acids. The biological activity of IL-1 obtained from E. coli is comparable to that of the natural protein, while the protein produced from yeast showed very low specific activity. The analysis of the state of oxidation of the two cysteine residues present in the IL-1 molecule and the evaluation of the immunoreactivity of the two proteins have proved that a different conformation is at the basis of the different biological activity of the two proteins.