Method of purifying a long-acting human growth hormone

The present invention relates to a long-acting human growth hormone NexP-hGH protein and its production method. More specifically, it relates to a specific isoform of long-acting human growth hormone NexP-hGH protein in which human growth hormone is fused with a highly glycosylated alpha-1 antitrypsin mutant whereby long-acting properties in vivo are increased. The present invention also relates to a high-purity purification method for NexP-hGH, which includes the steps of: (a) carrying out anion-exchange resin chromatography on a biological emulsion comprising NexP-hGH in which human growth hormone is fused with an alpha-1 antitrypsin mutant; (b) carrying out hydrophobic resin chromatography on the biological emulsion comprising NexP-hGH, or on the eluate produced in step (a); and (c) carrying out affinity chromatography, entailing packing with a resin to which anti-alpha-1 antitrypsin antibody fragments are attached, on the biological emulsion comprising NexP-hGH and on the eluate produced in step (a) or step (b).