Abstract
ABSTRACT
DNA methylation is one of the most important epigenetics event and has been
one of the most adequately studied epigenetics event. The process of DNA
methylation will significantly influence the expression of genes. Alterations of
methyltransferases activity may lead to aberrant DNA methylation patterns that are
associated with several genetic diseases and various types of cancer. Thus, sensitive
activity assay and inhibitor (anti-methylation drugs) screening for MTases represent a
valuable strategy to both clinical diagnostics and therapeutics. This thesis is
concentrated on study the activity of methyltransferases and design colorimetric
sensor based on AuNPs. The main contents of this thesis are as follows:
1. This section introduced DNA methylation and colorimetric sensor based on
AuNPs. DNA methylation, a common gene protection approach, plays an important
role in both prokaryotes and eukaryotes. It is extremely important to lots of normal
cellular processes including development, transcriptional silencing, gene regulation,
and X chromosome inactivation, among others. At present, the main approaches to
study DNA methylation are analysis the activity of methyltransferases and the
corresponding inhibitors. With the advantages of AuNPs, such as biological
compatibility, easy to modifyed the surface, color changed obviously after
aggregation, the colorimetric sensor based on AuNPs are widely used in biological
detection.
2. For the past few years, electrochemical sensor is the most common used
sensor for methyltransferases assay. In order to enrich the research methods, this work
developed colorimetric sensor for M.SssI activity. We adopted the well designed HPI
as methylated substrate and the ssDNA modified on AuNPs acted as probe DNA. The
aggregation of AuNPs was based on the hybridization of DNA. Our method response
well to the concentration of M.SssI in the range from 2 to 50 U/mL with the detection
limit of 0.84 U/mL. The proposed method is simple with high selectivity.
3. We present a colorimetric method for the assay of DNA methyltransferase
(MTase) activity based on strand displacement amplification (SDA). In our design,
