C60 affects DNA replication in vitro by decreasing the melting temperature of DNA templates

The effect of C60 on DNA replication in vitro was studied by a quantitative real-time polymerase chain reaction (QPCR) system using a designed 110bp single-stranded DNA as the template. The results indicated that the efficiency of QPCR can be dramatically enhanced by C60 at the beginning of the exponential phase, and that QPCR production can be significantly inhibited by C60 at later cycles or at the plateau, which is the period represented by an interesting inverted U-shaped time response curve. Two different sized double-stranded DNA fragments (110bp and 60bp) were used to investigate the possible interaction between C60 and DNA. The melting curve results showed that C60 significantly decreased the melting temperatures (Tm) of the DNA fragments. By changing the concentrations of the initial DNA templates or C60 in the QPCR system, we found that the decreased Tm value of DNA templates by C60 is the primary reason for the increased QPCR efficiency. Our findings are consistent with the conclusions of other studies that C60 can disrupt DNA replication in vitro by binding to DNA and changing the conformation of DNA templates.