Amplification of target DNA in vitro via polymerase chain reaction (PCR) is a widely used scientific technique in molecular biology. This method relies on repeated heating and cooling cycles of the DNA and enzyme mixture, resulting with the enzymatic replication of the DNA. A heat stable Taq DNA polymerase and a thermal cycler that enables repeated heating/cooling cycles are the two key components of the PCR. In this study we have produced a high activity Taq DNA polymerase and used this enzyme to validate and optimize two newly developed thermal cyclers- a conventional and a capillary thermal cycler. Taq DNA polymerase gene was amplified from Thermus aquaticus DNA, was cloned and overexpressed using Gateway&reg / recombination cloning technology. Highly active Taq DNA polymerase enzyme was purified from E.coli and its activity was tested by PCR, using different sources of DNA. Our results showed that the enzyme activity of the produced Taq DNA polymerase was not significantly different from the commercial available Taq DNA polymerase. To further characterize the purified enzyme, endonuclease and nicking activities were also tested to be absent. The fidelity of the purified Taq DNA polymerase was also tested and found to be the same as the commercially available Taq polymerases. In this study, in addition to the production of a Taq polymerase, optimization studies for two new thermal cyclers, a conventional and a capillary, was also carried out. The conventional thermal cycler was found to be as efficient as the commercially available thermal cyclers in the 95% confidence interval. The capillary thermal cycler was tested as a proof of concept and our results showed that it works less efficiently due to the insufficient insulation and capillary tubes being longer than the capillary tube holder.

Apart from the p53 protein, the TP53 tumor-suppressor gene is expressed as another eleven protein isoforms with the use of alternative splicing, alternative promotors and alternative translational initiation sites. Abnormal expression of these isoforms has been observed in tumor tissues. The binding properties as well as the biological functions are also modulated, due to sequential and therefore structural differences from the p53 protein. p53 is regulated by these isoforms in both suppressive and supportive manner. Explanation of the p53 isoform regulation mechanism in cells could lead to desired alternative splicing of the chosen isoforms, and modulation of isoform expression could be used in cancer treatment based on p53 therapy. Basic information about p53 protein is summarised in the theoretical part of this master thesis, supplemented with recent advances in the field of p53 isoforms, as well as the Gateway cloning method. The main goal of the experimental part was p53 isoform production in a bacterial expression system. Prior to the protein production, DNA sequences coding twelve p53 isoforms were prepared using PCR and Gateway cloning. In total, twelve entry clones and eight expression clones were prepared by cloning the isoforms’ sequences. After the protein production and purification, the detection using SDS-PAGE and Western Blotting was performed with five p53 protein isoforms: p53, 40p53, 40p53 and 40p53. DNA binding properties of p53 protein isoforms will be tested in subsequent research.