dipolar ions

di·po·lar i·ons

ions possessing both a negative charge and a positive charge, each localized at a different point in the molecule, which thus has both positive and negative "poles"; amino acids are the most notable dipolar ions, containing a positively charged NH3+ group and a negatively charged COO- group at neutral pH.
Synonym(s): amphions, zwitterions

di·po·lar ions

(dī-pō'lăr ī'onz)
Ions possessing both a negative charge and a positive charge, each localized at a different point in the molecule, which thus has both positive and negative "poles."
Synonym(s): zwitterions.
References in periodicals archive ?
A justification for the constant field assumption can be found in the observation that if a membrane contains a large number of dipolar ions close to their isoelectric point, these dipoles will tend to alter their orientation in such a way that they tend to smooth out any irregularities and maintain a constant field [7].