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Isoelectric point. The isoelectric point (pI, pH (I), IEP), is the pH at which a molecule carries no net electrical charge or is electrically neutral in the statistical mean. The standard nomenclature to represent the isoelectric point is pH (I). [1] However, pI is also used. [2] For brevity, this article uses pI.
The point of zero charge is the pH value for which the net surface charge of adsorbent is equal to zero. This concept has been introduced by an increase of interest in the pH of the solution during adsorption experiments. [1] The reason is that the adsorption of some substances is very dependent on pH. The pzc value is determined by the ...
The isoionic point is the pH value at which a zwitterion molecule has an equal number of positive and negative charges and no adherent ionic species. It was first defined by S.P.L. Sørensen, Kaj Ulrik Linderstrøm-Lang and Ellen Lund in 1926 [1] and is mainly a term used in protein sciences. It is different from the isoelectric point (p I) in ...
The iso-electric point is the pH value at which the zeta potential is approximately zero. At a pH near the iso-electric point (± 2 pH units), colloids are usually unstable; the particles tend to coagulate or flocculate. Such titrations use acids or bases as titration reagents. Tables of iso-electric points for different materials are available.
[72] [73] [74] The isoelectric point of a given molecule is a function of its pK values, so different molecules have different isoelectric points. This permits a technique called isoelectric focusing, [75] which is used for separation of proteins by 2-D gel polyacrylamide gel electrophoresis. Buffer solutions also play a key role in analytical ...
The isoelectric point is the pH at which a compound - in this case a protein - has no net charge. A protein's isoelectric point or PI can be determined using the pKa of the side chains, if the amino (positive chain) is able to cancel out the carboxyl (negative) chain, the protein would be at its PI.
The perpendicular spoke will point to the heart's electrical axis. To determine which numerical value should be used, observe the polarity of the perpendicular lead on the ECG. [clarification needed] For example, if the most isoelectric (or equiphasic) lead is aVL, the perpendicular lead on the hexaxial reference system is lead II.
At the isoelectric point the relationship between the dielectric constant and protein solubility is given by: log S = k / e 2 + log S 0 {\displaystyle \log S=k/e^{2}+\log S^{0}\,} S 0 is an extrapolated value of S , e is the dielectric constant of the mixture and k is a constant that relates to the dielectric constant of water.