Supplementary Figure 8: Effect of viscosity, temperature, and pH on the sensor readout.
From: A sensor for quantification of macromolecular crowding in living cells
(a) Effect of glycerol on the sensor readout. A solution of 10 mM NaPi, pH 7.4 was mixed with a 85% (v/v) solution of glycerol to obtain the desired concentration of glycerol. Glycerol did not affect the readout, showing that the sensor does not report viscosity changes. (b) Effect of temperature on the sensor readout with and without Ficoll. Conditions: 10 mM NaPi, 100 mM NaCl, 2 mg/ml BSA, pH 7.4. A small temperature dependence is observed both in the presence and absence of Ficoll. (c) Effect of pH on the sensor readout. Conditions: 10 mM NaPi. Below pH 7 the FRET ratio drops, indicating measurements should be performed at pH >7. The drop in FRET ratio at pH <7 is likely due to protonation of the glutamates in the α-helices.
