DNA methyltransferases: activity minigel analysis and determination with DNA covalently bound to a solid matrix

We describe two methods that facilitate detection and characterization of DNA methyltransferases: activity gel analysis and the use of DNA-cellulose or DNA-Sepharose in DNA methylation reactions. The first permits identification of catalytic subunits, determination of the influence of proteolysis, and evolutionary or developmental studies. The second allows accurate and fast determination of DNA methyltransferase activities in crude extracts and during purification.