(Left) Variation of fluorescein emission as a function of temperature in 20 mM HEPES, pH 7.4, with 1 mM NaCl. SLIIb alone (open triangles, TM1 = 304.6 ± 0.8, TM2 = 329.3 ± 0.3), SLIIb plus 50 µM GGHYrFK-amide (1) (black squares, TM1 = 325.3 ± 3.8, TM2 = 330.8 ± 0.4), SLIIb plus 50 µM GGhyrfk-amide (2) (open circles, TM1 = 317.8 ± 5.9, TM2 = 332.3 ± 0.9). Fits are shown to a three state consecutive melt model, with the proposed melts corresponding to TM1 and then TM2 (model shown on the right).