overview of purification, biological activities and therapeutic applications of thymosin alpha

Thymosin alpha 1 [T alpha 1] is 28 amino acid residues peptide. Thymic epithelial cells produce acetylated N-terminal T alpha 1 that has powerful immunostimulatory and antitumor activites. Inside the body T alpha 1 effects endocrine, immune and central nervous system. T alpha 1 can be purified by using fractionation procedures from thymus. Many recombinant DNA techniques are being used for the production of T alpha 1. In addition T alpha 1 is being expressed as fusion proteins with other therapeutically important proteins. For the high-throughput production of T alpha 1, different expression systems are being used such as E.coli and yeast. T alpha 1 has unique antitumor and immunoregulatory properties and also have capacity to protect cells from oxidative damage. T alpha 1 has many therapeutic applications specifically against many infectious diseases [hepatitis B and C, AIDS, SARS etc.] and cancer

Construction and application of a yeast expression system for thymosin a1

We want to construct a yeast expression system for thymosin a1 (Ta1) to make the orally administered Ta1 preparation possible. The whole Ta1 DNA fragment was obtained by PCR. After being digested with restriction enzymes, it was cloned into pYES2 vector. Sequencing was performed to identify the recombinant. The sequence of Ta1 in recombinant coincided with the original one reported in Genbank. When pYES2-Ta1 plasmid was transformed into yeast, galactose instead of glucose was used to induce Ta1 expression. Western blot was performed to identify the quality of the expressed Ta1. Dried yeast containing pYEST2-Ta1 was fed to Balb/c mice whose immunities were inhibited by cyclophosphamide in advance. Synthesized Ta1 peptide was used as positive control and empty yeast was used as negative control. Compared with the negative control group, both dried yeast containing pYEST2-Ta1 and synthesized Ta1 peptide can significantly increase the CD8+ level (22.74±1.09 and 18.77±4.72 vs 7.49±2.14, p<0.01), while both of them had little effect on the CD4+ lymphocytes (61.86±6.94 and 65.91±4.78 vs 57.93±10.40, p>0.05). We concluded that a high effective yeast expression system for Ta1 was constructed successfully and the Ta1 protein expressed by this system can improve CD8+ level in immune inhibited mice.