sigmoidal, 4pl model of regression analysis  (GraphPad Software Inc)

Journal: Nature Communications

Article Title: Structural basis and synergism of ATP and Na + activation in bacterial K + uptake system KtrAB

doi: 10.1038/s41467-024-48057-y

Figure Lengend Snippet: a , b Left panels: intrinsic tryptophan fluorescence-based urea unfolding assays of ATP-BsKtrA in ( a ) K + Buffer titrated against NaCl and in ( b ) Na + Buffer titrated against KCl, respectively. Right panels: the C m values plotted against [Na + ] and [K + ], respectively. The C m values were calculated by fitting the data to a sigmoidal 4PL model using GraphPad Prism. Refer to Supplementary Fig. for original fluorescence data. c , d Differential scanning fluorimetry (DSF) assays demonstrating the T m of ( c ) ATP-BsKtrA and ( d ) ATP-BsKtrA E125Q titrated with NaCl (blue bars) and KCl (green bars). Data represent the mean ± s.d. with ( c ) n = 6 and ( d ) n = 4 independent experimental replicates. Inset c , the apparent dissociation constant ( K dapp ) of Na + binding with ATP-BsKtrA. The K dapp was analyzed by fitting the fraction bound derived from the DSF assays against the concentrations of NaCl to a one-site model using GraphPad Prism. Refer to Supplementary Fig. for raw data. e Half-life constants of BsKtrA in the presence of Na + (blue bars) and K + (green bars). The half-life constants were determined by GraphPad Prism using exponential one-phase decay model. Data represent the mean ± s.d.; n = 4 independent experimental replicates. Statistical analyses were performed using two-way ANOVA. Refer to Supplementary Fig. for raw data. Source data for a – e are provided as a Source Data file.

Article Snippet: The C m values were calculated by fitting the data to a sigmoidal 4PL model using GraphPad Prism.

Techniques: Fluorescence, Binding Assay, Derivative Assay