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

The effect Of C-60 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 C-60 at the beginning of the exponential phase, and that QPCR production can be significantly inhibited by C-60 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 C-60 and DNA. The melting curve results showed that C-60 significantly decreased the melting temperatures (Tm) of the DNA fragments. By changing the concentrations of the initial DNA templates Or C-60 in the QPCR system, we found that the decreased Tm value of DNA templates by C-60 is the primary reason for the increased QPCR efficiency. Our findings are consistent with the conclusions of other studies that C-60 can disrupt DNA replication in vitro by binding to DNA and changing the conformation of DNA templates. (C) 2009 Published by Elsevier Ltd.