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. Author manuscript; available in PMC: 2016 Mar 21.
Published in final edited form as: Biochemistry. 2015 Oct 13;54(42):6545–6554. doi: 10.1021/acs.biochem.5b00876

Figure 4.

Figure 4

Reverse titration by ITC indicates existence of specific and nonspecific binding. Titration of RNA (stem IIB or stem IA) into Rev–ARM at 0.1 M (A, B) and 0.3 M (C, D) KCl. Top panels show ITC traces, and bottom panels show integrated heat values. Isotherms are distinctly biphasic at 0.1 M KCl, reflecting both nonspecific and specific binding behavior, and are monophasic at 0.3 M KCl, reflecting exclusively specific binding. Traces appear similar at 10, 20, and 30 °C, for which data were collected and analyzed. Data were fit using the finite-lattice competitive binding model32,33 at 0.1 M KCl (A, B) and the single-site binding model at 0.3 M KCl (C, D).