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BioMed Research International
Volume 2013 (2013), Article ID 107238, 8 pages
Research Article

Extending the Serum Half-Life of G-CSF via Fusion with the Domain III of Human Serum Albumin

State Key Laboratory of Natural Medicines, School of Life Science and Technology, China Pharmaceutical University, Tongjiaxiang 24, Nanjing 210009, China

Received 28 April 2013; Revised 3 August 2013; Accepted 7 August 2013

Academic Editor: Chang-Yang Gong

Copyright © 2013 Shuqiang Zhao et al. This is an open access article distributed under the Creative Commons Attribution License, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.


Protein fusion technology is one of the most commonly used methods to extend the half-life of therapeutic proteins. In this study, in order to prolong the half-life of Granulocyte colony stimulating factor (G-CSF), the domain III of human serum albumin (3DHSA) was genetically fused to the N-terminal of G-CSF. The 3DHSA-G-CSF fusion gene was cloned into pPICZαA along with the open reading frame of the α-factor signal under the control of the AOX1 promoter. The recombinant expression vector was transformed into Pichia pastoris GS115, and the recombinant strains were screened by SDS-PAGE. As expected, the 3DHSA-G-CSF showed high binding affinity with HSA antibody and G-CSF antibody, and the natural N-terminal of 3DHSA was detected by N-terminal sequencing. The bioactivity and pharmacokinetic studies of 3DHSA-G-CSF were respectively determined using neutropenia model mice and human G-CSF ELISA kit. The results demonstrated that 3DHSA-G-CSF has the ability to increase the peripheral white blood cell (WBC) counts of neutropenia model mice, and the half-life of 3DHSA-G-CSF is longer than that of native G-CSF. In conclusion, 3DHSA can be used to extend the half-life of G-CSF.