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ISSN 1672-9145 Acta Biochim Biophys Sin 2005, 37(2): 147–151 CN 31-1940/Q

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Overexpression of Soluble Human Thymosin Alpha 1 in Escherichia coli

Pei-Fu CHEN, Hong-Ying ZHANG¹, Geng-Feng FU, Gen-Xing XU¹, and Ya-Yi HOU*

Medical School, Nanjing University, Nanjing 210093, China;

¹School of Life Sciences, Nanjing University, Nanjing 210093, China

Abstract Synthesized gene of human thymosin alpha 1 (Ta₁) was inserted into pET-28a, pET-9c, pThioHis B, pGEX-2T or pBV222 and then inductively expressed in strains of Escherichia coli. Among the five expression systems, the BL21/pET-28a system provides the highest expression level of fusion protein in a soluble form, which is up to 70% of total expressed bacterial proteins as visualized by sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The resulting fusion protein purified through nickel affinity chromatography accounts for 2.53% of the wet bacterial pellet weight and reaches 94.5% purity by SDS-PAGE. These results indicate the potential of this expression system for high-throughput production of recombinant Ta₁.

Key words human thymosin alpha 1; Escherichia coli; fusion expression; Ni2+ affinity chromatography

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Received: October 27, 2004 Accepted: January 6, 2005

*Corresponding author: Tel/Fax, 86-25-83686441; E-mail, [email protected]