Effects of oligonucleotide secondary structure formation on RecJ processivity. The PAGE image (A) demonstrates how S11, because of its increased level of secondary structure formation, is resistant to digestion by RecJ alone (lane 2) compared to treatment with RecJ and SSBP in combination (lane 3); lanes 4−6 show S12 before and after RecJ and RecJ−SSBP treatment (30 min, 37 °C). (B) Energy dot plots for S11 (I) and S12 (II−IV). The ΔG Gibbs free energy for S11 (37 °C) was measured at −11.49 kcal/mol (I)17 and for S12 at −3.74 kcal/mol (II), −3.04 kcal/mol (III), and −2.83 kcal/mol (IV). For tests run (A), 1 μM reactions were used accordingly: 30 units of RecJ (lanes 2 and 5), 30 units of RecJ and 0.5 μg of SSBP (lanes 3 and 6), and controls for S11 and S12 in which neither RecJ nor SSBP was applied (lanes 1 and 4). Gel analysis was performed on 15% PAGE with urea (120 V for 60 min). (Off) labels in panel A denote trityl-off oligonucleotide strands.