Isoelectric Point
Isoelectric Point - Related Videos
10:19
Induction of an Isoelectric Brain State to Investigate the Impact of Endogenous Synaptic Activity on Neuronal Excitability In Vivo
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Cited by 3 •
2016
This procedure performs long-lasting in vivo intracellular recordings from single neurons during physiologically relevant cerebral states and after complete abolition of ongoing electrical activities, resulting in an isoelectric brain state. The physiological constants of the animal are carefully monitored during the transition to the artificial comatose condition.
03:11
Liquid Phase Isoelectric Focusing: An Electrophoresis Technique to Separate Bioactive Molecules from Crude Gymnema sylvestre Extract
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2025
This video describes a technique to separate complex molecules from plant extracts using liquid phase isoelectric focusing. This technique helps purify complex biomolecules in their native state which can be used for various downstream applications.
07:58
Highly Sensitive and Quantitative Detection of Proteins and Their Isoforms by Capillary Isoelectric Focusing Method
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2018
Capillary isoelectric focusing is an antibody-based, ultrasensitive, high throughput technique, enabling detailed characterization of proteins and their isoforms from extremely small biological samples. The following describes a protocol for detection and quantification of specific proteins and their isoforms in an automated and robotized manner.
09:57
Separation of Bioactive Small Molecules, Peptides from Natural Sources and Proteins from Microbes by Preparative Isoelectric Focusing (IEF) Method
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Cited by 4 •
2020
The objective is to fractionate and isolate bioactive small molecules, peptides from a complex plant extract, and proteins from pathogenic microbes by employing liquid-phase isoelectric focusing (IEF) method. Further, the separated molecules were identified and their bioactivity confirmed.
09:10
Synthesis of Masarimycin, a Small Molecule Inhibitor of Gram-Positive Bacterial Growth
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2022
A detailed protocol is presented for preparing the bacteriostatic diamide masarimycin, a small molecule probe that inhibits the growth of Bacillus subtilis and Streptococcus pneumoniae by targeting cell wall degradation. Its application as a chemical probe is demonstrated in synergy/antagonism assays and morphological studies with B. subtilis and S. pneumoniae.
FAQs
The pKa values of ionizable groups indicate the pH ranges in which those groups gain or lose protons. As pH moves across these ranges, the molecule’s positive and negative charge contributions change. The isoelectric point therefore reflects the combined behavior of its ionizable groups, rather than the behavior of a single functional group in isolation.
An amphoteric molecule can carry both positively and negatively charged groups while having an overall charge of zero. At the isoelectric point, these opposing contributions balance rather than disappear. This distinction matters when interpreting charge-based behavior, because the molecule still contains ionizable sites that can respond to changes in pH.
Near the isoelectric point, reduced net charge generally weakens electrostatic repulsion between molecules. With less repulsion, molecules can approach one another more readily, which may encourage aggregation and precipitation. This relationship connects molecular charge to observable sample stability and helps explain why pH control is important for amphoteric molecules.
Changing pH shifts the protonation state of ionizable groups according to their pKa values. Moving away from the isoelectric point increases the imbalance between positive and negative charge contributions, whereas conditions near the point reduce the net charge. These changes can affect solubility, aggregation, and behavior in charge-dependent analytical methods.
Electrophoretic separation relies on differences in molecular charge and movement under an applied electric field. The isoelectric point identifies the pH at which a protein or other amphoteric molecule has no net charge, providing a reference for interpreting its migration behavior. Comparing molecules with different charge characteristics can support their separation and analysis.
Knowing a protein’s isoelectric point helps researchers select and control pH conditions during purification or formulation. Because solubility and aggregation often change near this point, pH can influence whether material remains dispersed or precipitates. This information supports strategies for separating proteins and for maintaining desired stability in prepared samples.