Interleukin-33 Human Recombinant produced in E.Coli is a single, non-glycosylated, Polypeptide chain containing 159 amino acids C-terminal fragment (112-270) having a molecular weight of 20.5kDa and fused with a 4.5kDa amino-terminal hexahistidine tag. The IL-33 His is purified by proprietary chromatographic techniques.