After defining standards, a hyperbola curve fit can be used to create a standard curve in the MARS Data Analysis software. A hyperbola fit is commonly used to calculate one-site binding constants (KD) for the interaction of two proteins or for a protein-ligand interaction. The binding or affinity constant (KD), which is expressed in molarity, can be derived from a hyperbola fit curve by calculating 50% of the response of the y-axis, that is when the first protein is half saturated with the second protein or ligand. In MARS after performing a hyperbola fit, the KD value is equivalent to the ‘b’ value found under the Standard Curve Fit Results.
The figure uses the hyperbola fit and it was derived from data using the SoPRanoTM label-free assay from Pharma Diagnostics. It measure the interaction of varying concentrations of an antibody with an antigen.