Electrochemical biosensing method for the detection of DNA methylation and assay of the methyltransferase activity

In this article, we presented an electrochemical method for detection of DNA methylation and assay of DNA methyltransferase (MTase) activity using methylene blue (MB) as electrochemical indicator. After the DNA hybrid was methylated by T. aq I MTase, it could not be cleaved by Hinc II endonuclease. On the contrary, the double DNA without methylation could be cleaved, which would decrease the amount of intercalated MB. Thus, the DNA methylation status and MTase activity could be determinated based on the voltammetric signal change of MB. The methylation site could be found based on this method. The electrochemical signal of MB increased linearly with increasing T. aq I MTase concentration from 0.1 to 100   U/mL. Moreover, the inhibition investigation demonstrated that fisetin could inhibit the T. aq I MTase activity with the IC 50 value of 280   μM. Therefore, the screening of the inhibitors of MTase could be accomplished using the novel method.