Supplementary Figure 7: Effect of small molecules and ions on the sensor readout. | Nature Methods

Supplementary Figure 7: Effect of small molecules and ions on the sensor readout.

From: A sensor for quantification of macromolecular crowding in living cells

Supplementary Figure 7

(a) Effect of NaCl on the sensor readout. NaCl was titrated from a 5M stock solution into a 1.0 ml solution of the sensor with the corresponding amount of Ficoll, and 10 mM NaPi, 2 mg/mL BSA, pH 7.4. The FRET ratio does not change due to NaCl, irrespective of the Ficoll concentration, demonstrating that electrostatic effects do not influence the read-out. A very small decrease can be observed at higher salt concentrations as more stock solution of salt is added, diluting the Ficoll, which in turn results in less crowding. (b) Effect of potassium glutamate on the sensor readout. Titration up to 500 mM glutamate from a 5M stock solution does not alter the readout of the sensor, demonstrating that electrostatic effects do not influence the readout. Conditions: 10 mM NaPi, 2 mg/ml BSA, pH 7.4. Addition of glutamate did not alter the pH significantly. (c) Effect of glycine betaine on the sensor read-out. Titration of up to 1M glycine betaine does not alter the readout of the sensor. Conditions: 10 mM NaPi, 2 mg/ml BSA, pH 7.4. (d) Effect of DNA on the sensor readout. DNA does not have an effect on the sensor. Conditions: 10 mg/ml salmon testes DNA, 10 mM NaPi, 100 mM NaCl, 0.1 mg/ml BSA, pH 7.4.

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