5. Conclusion
In summary, we have successful produced IL-18 mutation variants fromE. coli expression system. Although the most of protein was expressed as inclusion body, we accomplished the refolding method yielding the soluble form of IL-18 with activity. From all of results we presented, the mutation of surface cysteine to serine of IL-18 DM could reduce the aggregation prone while enhanced the activity. Despite the deep mechanism of this scenario has not been elucidated, the possibility may be from the structural changes that led to the more appropriate form of IL-18 and receptor binding. The increase of active IL-18 resulted from the lower aggregation rate may also help it activity. Further study regarding to the mechanism of this scenario must be useful to apply for other proteins or biologic drugs.