ATP hydrolysis during unwinding 4-strand complementary junctions.

<p>Junctions of varying arm lengths (shown in b.p.) were used to measure the rate of ATP hydrolysis during unwinding. RecG was pre-incubated with junction and the reactions were initiated by rapid mixing with ATP and heparin. Final concentrations are 200 nM DNA junction (A∶B′∶C∶D), 10 nM RecG, 200 µM ATP, 1 mg ml⁻¹ (55.5 µM) heparin and 5 µM MDCC-PBP. The reactions were performed in the presence of a P_i mop, described in <a href="http://www.plosone.org/article/info:doi/10.1371/journal.pone.0038270#s4" target="_blank">materials and methods</a>. Inset: Effect of heparin on ATPase activity of RecG during unwinding. The reactions were initiated by rapidly mixing the pre-incubated RecG.DNA (A40:B′40:C19) with ATP with or without heparin. In another measurement (“control”), RecG was pre-incubated with heparin and then rapidly mixed with DNA junction (A40:B′40:C19) plus ATP. Final concentrations are 200 nM DNA junction, 10 nM RecG, 200 µM ATP, 2 mg ml⁻¹ (111 µM) heparin and 5 µM MDCC-PBP with P_i mop.