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. 2012 Aug 14;7(8):e43072. doi: 10.1371/journal.pone.0043072

Figure 1. pH response of purified pHlash protein in vitro.

Figure 1

(A) Normalized luminescence emission spectra of pHlash with 10 µM native coelenterazine at pH 5.4–9.0 (legend shown at right) of purified pHlash protein in 50 mM BIS-Tris-propane, 100 mM KCl, and 100 mM NaCl. Luminescence intensity was normalized to the peak at 475 nm (non-normalized data shown in Figure 2). (B) Construct of the pHlash fusion protein. Rluc8 was linked to cpVenus by the sequence Ala-Glu-Leu. (C) The BRET ratio (luminescence at 525 nm:475 nm) as a function of pH is shown for pHlash in vitro. Error bars are +/− S.D., but in most cases the error bars are so small that they are obscured by the symbols (n = 3).