Isoelectric Point Plugin

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

    Introduction

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

    The Isoelectric Point Plugin calculates the net charge of a molecule as a function of pH. The result appears in a separate window that shows 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.

    images/download/attachments/1806643/isoelectricpoint.png

    Fig. 1 Isoelectric Point Plugin result window

    Options

    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. The step size of the pH axis of the plot can be set.

    • Keep explicit hydrogens: the explicit H atoms of the result molecule are kept if this option is enabled

    • Consider tautomerization/resonance: the calculation is performed on the major tautomer form of the input molecule if this option is enabled

    images/download/attachments/1806643/iep_panel.png

    Fig. 2 Isoelectric Point Options window