The result of equilibrium-constant calculations strongly depends on the evaluation method used and on the type of experimental errors

The determination of equilibrium constants is a widespread tool both to und erstand and to characterize protein-protein interactions. A variety of diff erent methods, among them Scatchard analysis, is used to calculate these co nstants. Although more than 1000 articles dealing with equilibrium constant s are published every year, the effects of experimental errors on the resul ts are often disregarded when interpreting the data. In the present study w e theoretically analysed the effect of various types of experimental errors on equilibrium constants derived by three different methods. A computer si mulation clearly showed that certain experimental errors, namely inaccurate background correction, inexact calibration, saturation effects, slow kinet ics and simple scattering, can adversely affect the result. The analysis fu rther revealed that, for a given type of error, the same data set can produ ce different results depending on the method used.