Chemically-modified UNG (Uracil-N-Glycosylase) enzyme and modification method and application thereof

The invention discloses a chemically-modified UNG (Uracil-N-Glycosylase) enzyme. The chemically-modified UNG enzyme is a UNG enzyme modified by anhydride. The chemically-modified UNG enzyme cannot show enzyme activity at a certain temperature or below, and after being incubated for a certain period of time at a specific temperature, the chemically-modified UNG enzyme can regain normal activity after modification removal, so that the activity controllability is achieved. The invention further provides a method for modifying the UNG enzyme by using the anhydride, and the application of the chemically-modified UNG enzyme. By the method for modifying the UNG enzyme by using the anhydride, the chemically-modified UNG enzyme can be prepared. When the chemically-modified UNG enzyme is applied to EMA (Enzymes-Mediated-Amplification) (namely enzymes-mediated nucleic acid normal temperature amplification method) or other isothermal nucleic acid amplification methods, an amplification product can be prevented from polluting a reaction system and the environment, the time consumption is low, operation is simple and the activity is controllable.