The present invention is directed to the cells, compositions, and methods for the production of and purification of recombinant
protein. In particular, the invention is directed to have enhanced soluble expression of
interleukin 1-
receptor antagonist by means of an optimized novel
polynucleotide sequence and host transformed with the said
polynucleotide. The invention also provides a method for increased production and purification of
interleukin 1-
receptor antagonist (IL-1Ra) wherein, the
polynucleotide of the present invention is used to transform a suitable host resulting in over-expression of corresponding proteins and a method for isolating the expressed polypeptide. The invention also relates to the purification method for of
interleukin 1-
receptor antagonist (IL-1Ra) using multimodal
chromatography as well as characterization of properly folded of interleukin 1-
receptor antagonist (IL-1Ra)
protein.