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. Author manuscript; available in PMC: 2015 Aug 15.
Published in final edited form as: Bioorg Med Chem. 2014 Jun 2;22(16):4399–4406. doi: 10.1016/j.bmc.2014.05.049

Figure 6. DNA unwinding substrates containing a methylphosphonate (MeP) at varying positions.

Figure 6

Placement of MeP at different positions within the tracking strand of a helicase substrate was used to determine the number of base pairs that spontaneously melted during helicase-catalyzed unwinding. The loss of the negative charge on the DNA backbone due to the MeP was found to stop DNA unwinding activity of Dda helicase. Therefore, if melting was observed for a particular substrate in the presence of Dda helicase, the number of base pairs remaining in that duplex could serve as an estimate for spontaneous melting 37.