Cloning and Expression of Thymidine Kinase from Zebrafish Danio rerio

Objective: To clone the TK1 cDNA sequence of zabrafish,to express its protein in E.coli and to evaluate its biological activity.Method: The complete TK1 cDNA was amplified by RT-PCR and RACE.Expression vectors were induced by IPTG in E.coli BL21(DE3).TK1 protein was purified to homogeneity using Ni-NTA spin column.Result: The complete TK1 cDNA sequence was cloned,encoding a protein with a molecular weight of 26 kD.Conclusion: The purified zebrafish TK1 showed the highest biological activity,0.45 U/mg at 28℃.