Quantitative analysis of (−) and (+) strand DNA synthesis inhibition.

To estimate inhibition of (−) strand DNA synthesis, DCTs were introduced at the 3′ end or the penultimate position of DNA primers. When inhibition of DNA synthesis was evaluated using the “n+6” DNA synthesis assay, the percentage of inhibition was calculated as follow: 1- (% elongated product “+ DCT”/% elongated product “-DCT”). The percentage of elongated product in the presence or absence of DCT was the ratio “n+6”/(“n+6” + “n+3”). Alternatively, the percentage of inhibition was calculated based on inhibition of full-length (−) strand DNA synthesis (*). To study the effect of DCTs on (+) strand DNA synthesis, the nucleoside analogues were incorporated into 31-mer DNA templates. The percentage of inhibition of DNA synthesis was calculated as indicated in the legend of figure 5. *: percentage of inhibition obtained using the (−) strand strong-stop DNA synthesis assay; nd: not determined.