Figure 6: Activation of Y406A on model lipid membranes by slightly acidic pH.

From: Engineering a pH responsive pore forming protein

Figure 6

(a) Calcein release from LUVs. Red and black lines show calcein release at pH 6.5 and 8, respectively. Arrowhead indicates when Y406A was added to LUVs in solution in both cases. Acidification of the environment to pH 6.5 was achieved with addition of small volume of HCl at approximately 400 s (also indicated by an arrowhead). (b) SPR sensorgrams of LLO (black line) and Y406A (red line) activation experiment. Grey lines indicate when the solution coming from the flow cells was collected and used for fluorescence measurements. (c) Calcein fluorescence in fractions collected during the SPR assay presented in (b). Fraction “Buffer” represents a wash with a buffer with a pH of 5.7. 40 mM OG represent a washing step with detergent octyl-glucoside, which removed all remaining material from the surface of the sensor chip (two injections of OG across sensor chip are shown in (b), however, all calcein was released only during the first injection, which is presented in the graph).