Partial Purification of Human Parathyroid Hormone 1-84 as a Thioredoxin Fusion Form Expressed by Recombinant Escherichia coli in Aqueous TwoPhase System

The partitioning of Trx-hPTH(1-84) (human parathyroid hormone coupled with thioredoxin as a fusion partner) expressed by recombinant E. coli in the aqueous two-phase system(ATPS) comprised of PEG and salts was investigated. The effective factors on partition including the molecular weight and concentration of PEG, the types and concentration of salts and pH were evaluated. The maximum partitioning of the protein (K=3.4，Y=88.6%) was achieved in the ATPS when w(PEG 1000)=0.20 and w(MgSO4)=0.16 with the protein in the top PEG rich phase.