A simple computer program for Scatchard plot analysis of steroid receptors including non-specific binding correction on a low cost desk top calculator

Basic assay constants (samples [3H]-efficiency, specific activity and molecular weight of radioligand, incubation volume, cytosol volume and protein concentration) and experimental data as individual raw counts for T, NSB and B1 are keyed in manually to automatically entail the outprint of BF and B5 (mol/1) for each point. If no competed tubes for direct measurement of NSB are available, a “raw” Scatchard plot is drawn from which the asymptotic BF-value limB→∞BF=NSB can be read. This number is keyed in to serve as basis for the correction of the “raw” Scatchard values according to the method of Chamness and McGuire. The final result is presented by the outprint of number of calibration points, coefficient of correlation, y- and x-intercepts, affinity constant (KD and concentration of binding equivalents per ml incubation volume or per mg protein (in fmol) and the absolute number of binding sites per mg protein. The hardware required is a low cost desk top calculator (Hewlett Packard 97).