LIGAND BINDING - TUTORIAL #3 answer 3:1 - least squares fit of Y = [X]/(K+[X]) The use of least squares minimization is the soundest statistical way of analyzing the experimental data. You use the following equation to calculate the fraction of liganded sites: Y = [X] / (K + [X]) The following results are obtained: The equilibrium constant obtained is Kd = 1 mM (for the dissociation reaction: PX <==> P + X). Do the fit and the residuals look good? 1) Yes 2) No Back one step