Isoelectric point Calculator
Enter the three letter code (e.g. AlaGlyTyrGlu) or one letter code of amino acid sequence (e.g. APKHAY )
The isoelectric point is defined as the pH at which a particular amino acid sequence (peptide chain) bears no net electrical charge. At this pH the the amino acid sequence forms a zwitterion. The calculation is based on the pK values of the amino acids and of the terminal amine & carboxyl group of the peptide chain. Since different sources provide different values of pK values, we are averaging the isoelectric point values that are obtained using pKs from the following sources: Wikipedia , Lehlinger , Grimsley , Rodwell, Sillero & Solomon.