Abstract: Anhydride is capable of binding to and forming lysine polymer with DNA polymerase.Upon such modification, catalytic activity of Taq DNA polymerase is completely abolished during the preheating stage of PCR, thus minimizing non-specific amplifications and the formation of primer dimmers which interfere with efficient PCR amplification. Once exposed at high temperature for a while, such as 94℃ for 15min, anhydride could be removed from polymerase, resulting in almost full recovery of its catalytic activity, thus achieving hot-start PCR. Here in this paper, we chose an appropriate sort of anhydride to modify Taq DNA polymerase. We found that using such modified polymerase, sensitivity of PCR could be greatly improved by two orders of magnitude and 10 copies of the DNA molecule is now achievable for detection. In addition, the course of such modification was easy to handle and less cost. Moreover, modified polymerase was more stable, easy to store and show higher sensitivity and specificity. Therefore, the establishment of hot-start PCR system through chemical modification became one of the most crucial approaches to elevate the sensitivity and specificity for PCR, and was of great application value in the near future．

Key words: hot-start PCR, Taq DNA polymerase, chemical modification