Abstract：EMSA (electrophoresis mobility shift assay) is recently the most popular method to study the binding properties of nucleic transcription factors in vitro, meanwhile isotopes can cause damage to human body, which increases the complexity of operation. In this study, radioactive EMSA system was optimized to improve the stability of EMSA. Results indicated that, the purification of probes effectively reduced the background of autoradiography; the centrifugation of purified proteins facilitated to produce neat and clear bands; the use of a 350V voltage and 4°C temperature insured the stabilization of DNA-protein complexes during electrophoresis; the removal of radioactive liquid from gel and the adherence of gel to a piece of paper helped obtain clear autoradiography. Finally the optimized system effectively improved the stability of EMSA.
