IC50fit 4+

This program fits to vobs = v/(1+[I]/IC50) in the log form and so it gives pIC50 with standard errors. pIC50 is in the same format as a pKa i.e. it is -log(IC50). The Standard errors of pIC50 are log values and cannot be used to give a single standard error for the IC50 value.
The best way to obtain errors for IC50 is to determine the IC50 values 3 or more times and determine the mean IC50 value and its standard deviation.
If competitive inhibition is occurring and if the substrate concentration used is very much smaller than its Km then the IC50 value will equal the Ki for the competitive enzyme inhibitor. If this approximation does not hold then you can use the Cheng-Prusoff equation to estimate the Ki value from the IC50 value provided you know the substrate concentration and Km.
Data can be directly inputted and saved. If simple two column data in an excel file is saved as a csv file, then this program can read the csv file. Results can be saved, printed,copied and pasted into other applications such as Word.