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. Author manuscript; available in PMC: 2011 Oct 19.
Published in final edited form as: Biochemistry. 2010 Oct 19;49(41):8818–8830. doi: 10.1021/bi100557v

Figure 2.

Figure 2

Determination of the stoichiometry of binding of SgrAI to 18-2 and 18-1. A. Titration of 75 nM HEX labeled 18-2 in Buffer 2 (Table 1) at 4°C. The intercept of the two lines is 69 nM SgrAI dimer, indicating a 1:1 stoichiometry of SgrAI dimer to 18-2 duplex with 92% activity of SgrAI enzyme. B. Native PAGE gel shift of 100 nM 32P labeled 18-1 (of which 40% is double stranded). The intercept occurs at 55 nM SgrAI, suggesting 1:1 binding of 18-1 to SgrAI dimer with 73% enzyme activity. C. Titration of 100 nM HEX labeled 18-1 in Buffer 2 (Table 1) at 4°C. The first intercept at 109 nM SgrAI dimer indicates a 1:1 stoichiometry of SgrAI dimer to 18-1 duplex with 92% activity of SgrAI enzyme, the second intercept at 207 nM SgrAI dimer indicates a second SgrAI dimer binds the original 1:1 complex.