Isoelectric Point Plugin

    This manual gives you a walk-through on how to use the Isoelectric Point Plugin:


    The isoelectric point ( pI , or sometimes abbreviated asIEP) is the pH at which a particular molecule or surface carries no net electrical charge .

    The Isoelectric Point Plugin calculates the gross charge distribution of a molecule as a function of pH. The result appears in a separate window, containing the molecule with the pI and (if enabled) the pH:charge plot. Hovering the mouse over the points of the curve, the pH:charge value pairs appear.


    Fig. 1 Isoelectric Point Plugin result window


    The Isoelectric Point Options window offers the following options to set:

    • Decimal places: the number of decimal places used to display the results

    • Show charge distribution : enabling this option shows the calculated pH:charge plot on the result chart

    • pH step size : the step size for the prediction and display plot


    Fig. 2 Isoelectric Point Options window