zwitterion


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Related to zwitterion: isoelectric point

ion

 [i´on]
an atom or group of atoms having a positive (cation) or negative (anion) electric charge by virtue of having gained or lost an electron; substances forming ions are called electrolytes. adj., adj ion´ic.
dipolar ion an ion that has both positive and negative regions of charge.
hydrogen ion the positively charged hydrogen atom (H+), which is the positive ion of all acids. See also hydrogen ion concentration.
hydroxyl ion the negatively charged group, OH, present to excess in alkaline solutions.
Miller-Keane Encyclopedia and Dictionary of Medicine, Nursing, and Allied Health, Seventh Edition. © 2003 by Saunders, an imprint of Elsevier, Inc. All rights reserved.
Zwitterionclick for a larger image
Fig. 318 Zwitterion . Molecular structure of (a) undissociated amino acid, (b) Zwitterion.

zwitterion

the chemical form of an AMINO ACID with a dipolar ion state. The pH at which the amino acid exists as a zwitterion is called its ISOELECTRIC POINT and at this pH it will not migrate in an electric field, produced, for example, by ELECTROPHORESIS.
Collins Dictionary of Biology, 3rd ed. © W. G. Hale, V. A. Saunders, J. P. Margham 2005
References in periodicals archive ?
Figure 12 gives the effect of zwitterion, nonionic and anionic surfactants on modified clays' contact angles and Figure 13 shows the cationic surfactants effect.
The purpose of this study is to derive an approximate analytical solution for the prediction of the facilitation factor and permeation rate through liquid membranes for the facilitated transport of C[O.sub.2] where the reaction rate for C[O.sub.2] is expressed by the zwitterions reaction mechanism of Danckwerts (1979) and over a range from the moderate chemical reaction rate region to the chemical equilibrium region.
The initial attack of ozone occurs in both stressed and unstressed rubber to give a molozonide, which is unstable and dissociates to give a Zwitterion (1) and a carbonyl compound (2).
A possible explanation is that the highly polar zwitterions bonded to the glass-fiber surface, causing the evanescent wave sensor to lose sensitivity.
Hydroperoxide 21 is also a known product of the singlet oxygen-mediated oxidation of tryptophan, and it gets converted via its hydroperoxide isomer 22, zwitterion 23, and dioxetane 24 to N-formylkynurenine 25 [34, 55].
where L is dipeptide monoanion; HL is total zwitterion and neutral forms of dipeptide.
Bean et al., "Evaluation of in situ curable biodegradable polyurethanes containing zwitterion components," Journal of Materials Science: Materials in Medicine, vol.
First step is a 1,3 dipolar cycloaddition of ozone to the olefin leading to the malozonide (1) (Criegee intermediate), which is very unstable and decomposes to give a zwitterion (2) and a carbonyl compound (3) In the presence of reactive solvent, such as water or alcohol, the zwitterion interact with the solvent to give hydroperoxides (4) in high yield, since the concentration of the solvent far exceeds that of any other substances with which the zwitterion may react.
To describe this duplicity, the scientists coined the term "zwitterhormone," based on "zwitterion," a molecule containing both positively and negatively charged groups.
The reaction of the antiozonant with the ozonized rubber or zwitterion to form a self-healing film on the rubber surface (ref.
Actually, the presence of the zwitterion and protonated form of cysteine in 0.05 M HCl contributes to the adsorption of the inhibitor on cathodic active sites on the brass surface [1].