DNA methylation catalyzed by DNA methyl transferase (MTase) is a significant epigenetic process for modulating gene expression. Abnormal levels of DNA MTase enzyme have been regarded as a cancer biomarker or a sign of bacterial diseases. We developed a novel colorimetric method to assay M.SssI MTase activity employing peroxidase-like activity of DNA template Ag/Pt NCs without using restriction enzymes. Based on inhibiting the peroxidase reaction that occurred in the TMB-H₂O₂ system, in the presence of MTase, a highly sensitive and selective colorimetric biosensor was fabricated with a detection limit (LOD) of 0.05 U/mL and a linear range from 0.5 to 10 U/mL. The changes in absorption intensity were monitored to quantify the M.SssI activity. This strategy had a high selectivity over other proteins. Furthermore, it is also demonstrated that this method can be used for the evaluation and screening of inhibitors for DNA MTase.

DNA甲基转移酶（MTase）催化的DNA甲基化是调节基因表达的重要表观遗传过程。DNA MTase酶水平异常被认为是癌症的生物标志物或细菌性疾病的迹象。我们开发了一种新颖的比色法，无需使用限制酶即可利用DNA模板Ag / Pt NCs的过氧化物酶样活性来测定M.SssI MTase活性。基于抑制TMB-H ₂ O ₂中发生的过氧化物酶反应系统中，在MTase存在的情况下，制造了一种高灵敏度和选择性的比色生物传感器，其检测限（LOD）为0.05 U / mL，线性范围为0.5至10 U / mL。监测吸收强度的变化以定量M.SssI活性。该策略对其他蛋白质具有很高的选择性。此外，还证明了该方法可用于评估和筛选DNA MTase抑制剂。