zwitterionic

(adjective)

Pertaining to a neutral molecule containing both positive and negative charge.

Related Terms

  • halotolerance
  • osmoprotectant

Examples of zwitterionic in the following topics:

  • The Favorskii Rearrangement

    • A debate concerning the nature of the carbon-carbon bond formation step now favors direct (synchronous) formation of the cyclopropanone by a 1,3-elimination, as shown, rather than initial ionization of the enolate to a zwitterionic species such as that drawn in the green box.
    • When stereoisomeric substrates were examined, the rearrangement proved to be stereospecific, ruling out a common zwitterionic intermediate.
  • The Effect of pH on Solubility

    • The isomer on the right is a zwitterion.
  • Peptides & Proteins

    • As expected, the free amine and carboxylic acid functions on a peptide chain form a zwitterionic structure at their isoelectric pH.
  • α-Amino Acids

    • The resulting ammonium carboxylate structure, commonly referred to as a zwitterion, is also supported by the spectroscopic characteristics of alanine.
    • As expected from its ionic character, the alanine zwitterion is high melting, insoluble in nonpolar solvents and has the acid strength of a 1º-ammonium ion.
    • In the diagrams above is a display of an L-amino acid in its zwitterionic form.
    • Examples of a few specific amino acids may also be viewed in their favored neutral zwitterionic form.
    • At pH 6.00 alanine and isoleucine exist on average as neutral zwitterionic molecules, and are not influenced by the electric field.
  • Preparation of Ylides

    • This bonding stabilization extends to carbanions alpha to phosphonium and sulfonium centers, and the zwitterionic conjugate bases derived from such cations are known as ylides.
  • Reactions of Amino Acids

    • Once the carboxyl function is esterified, zwitterionic species are no longer possible and the product behaves like any 1º-amine.
    • Since amides are only weakly basic ( pKa~ -1), the resulting amino acid derivatives do not display zwitterionic character, and may be converted to a variety of carboxylic acid derivatives.
  • Extremely Halophilic Archaea

    • The most common compatible solutes are neutral or zwitterionic, and include amino acids, sugars, polyols, betaines and ectoines, as well as derivatives of some of these compounds.
  • Ions

    • Zwitterions are neutral and have both positive and negative charges at different locations throughout the molecule.
  • Synthesis of Amino Acids

    • If the racemic mixture of amides shown in the green shaded box above is treated with this enzyme, the L-enantiomer (whatever its rotation) will be rapidly converted to its free zwitterionic form, whereas the D-enantiomer will remain largely unchanged.
  • The Primary Structure of Peptides

    • A free amine function, usually in equilibrium with zwitterion species, is necessary for the initial bonding to the phenyl isothiocyanate reagent.
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