Purification of human interleukin-2 fusion protein produced in insect larvae is facilitated by fusion with green fluorescent protein and metal affinity ligand

The fusion protein of green fluorescent protein (GFP) and human interleukin -2 (hIL-2) was produced in insect Trichoplusia ni larvae infected with reco mbinant baculovirus derived from the Autographa californica nuclear polyhed rosis virus (AcNPV). This fusion protein was composed of a metal ion bindin g site (His)(6) for rapid one-step purification using immobilized metal aff inity chromatography (IMAC), UV-optimized GFP (GFPuv), enterokinase cleavag e site for recovering hIL-2 from purified fusion protein, and hIL-8 protein . The additional histidine residues on fusion protein enabled the efficient purification of fusion protein based on immobilized metal affinity chromat ography. In addition to advantages of GFP as a fusion marker, GFP was able to be used as a selectable purification marker; we easily determined the co rrect purified fusion protein sample fraction by simply detecting GFP fluor escence.