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. 2007 Apr 16;35(9):2924–2935. doi: 10.1093/nar/gkm126

Figure 4.

Figure 4.

Rapid burst kinetics of wild type and loop II variants. Insertion of dTTP into single nucleotide gapped DNA substrate 45T-22U-22D. Values in Table 2 were measured using the chemical quench-flow apparatus at 37°C. A preincubated cocktail of 100 nM loop mutant or WT and 300 nM gapped DNA was mixed with a cocktail of 100 μM dTTP containing 10 mM MgCl2. The reactions were quenched and monitored as described under the Materials and methods section. (A) The data for wild type were fit to the burst equation shown in the Materials and methods section. (B) An example of a loop mutant, 9-Ala, that exhibited rapid burst kinetics. Data were fit to the burst equation. The inset is an expansion of the Y-axis to show the points that define the burst. (C) Loopless does not exhibit rapid burst kinetics. Data were fit to a linear equation. (D–F) Examples of loop mutants with different residues, 5-Ala, Loop1- and Lambda-loop respectively, that exhibited rapid burst kinetics. Data were fit to the burst equation. The insets are an expansion of the Y-axis to show the points that define the burst. The kobs and steady-state constants for all loop mutants and wild type are listed in Table 3. The results are representative of at least three experiments.