ABSTRACT
Aim To study the mechanism of Escherichia coli DNA photolyase(EC 4.1.99.3) in repairing the ultraviolet induced pyrimidine dimmer lesions in DNA.Methods UV-Vis Specturum was used to measure the relationships between the enzyme activity and different state flavin ademine denucleotide(FAD).Results It was shown that the enzyme activity was the highest when FAD chromophore was in reduced state and lowest when it was in oxidated state,while the activity ranked between when the enzyme was in radical state.Partial denature was observed when the enzyme was in oxidated state and under over 30℃,yet the enzyme activity remained unchanged.The presence of MTHF chromophore enhanced the enzyme activity.Conclusion These findings provide clues for clinical application of DNA photolyase in the future.