Skip to main content
Back

Isoelectric Point definitions

Control buttons has been changed to "navigation" mode.
1/15
  • Isoelectric Point
    pH value where an amino acid's net charge is zero, resulting in the highest concentration of zwitterions.
  • Zwitterion
    Molecule with both positive and negative charges but an overall neutral charge, common at the isoelectric point.
  • pKa
    Numerical value indicating the acidity of a functional group, used to calculate isoelectric points.
  • Carboxyl Group
    Acidic functional group on amino acids with a typical pKa around 2, contributing to overall charge.
  • Ammonium Group
    Basic functional group on amino acids with a typical pKa around 9, often positively charged.
  • Side Chain
    Variable group on amino acids that can be acidic, basic, or neutral, affecting isoelectric point calculations.
  • Acidic Amino Acids
    Amino acids with side chains that donate protons, requiring special consideration in isoelectric point calculations.
  • Basic Amino Acids
    Amino acids with side chains that accept protons, influencing which pKa values are averaged for isoelectric point.
  • Cysteine
    Amino acid with a sulfur-containing side chain, treated uniquely in isoelectric point calculations.
  • Phenylalanine
    Amino acid without acidic or basic side chains, with an isoelectric point calculated by averaging carboxyl and ammonium pKa values.
  • Histidine
    Amino acid with a basic side chain containing nitrogen, requiring selection of the two most similar pKa values for isoelectric point.
  • Functional Group
    Specific group of atoms within a molecule responsible for characteristic chemical reactions, such as carboxyl or ammonium in amino acids.
  • Net Charge
    Sum of all positive and negative charges on an amino acid, which is zero at the isoelectric point.
  • Ionizable Group
    Part of a molecule capable of gaining or losing a proton, affecting the molecule's charge at different pH values.
  • pH
    Scale measuring hydrogen ion concentration, used to determine the charge state of amino acids and their isoelectric points.