Isoelectric Point (pI) Determination Service

Isoelectric point (pI) is one of the important physio-chemical parameters of macromolecules, which represents the pH when the overall net charge equals zero. The net charge of a particular molecule can be affected by the pH of surrounding environment, and the molecule can be more positively or negatively charged through the loss or gain protons. In addition, the pI of a molecule can influence the solubility its solubility at a certain pH and its overall pharmacokinetic behavior. Hence, it's essential to determine the pI of pharmaceutical products. Creative Proteomics will provide you with accurate and rapid pI determination according to ICH Q6B guidelines during drug development.

We Can Provide but Not Limited to:

The services we provide mainly include: 1) isoelectric point determination with isoelectric focusing (IEF); 2) isoelectric point determination with capillary isoelectric focusing (cIEF).

IEF and cIEF are two most commonly used techniques in determination of pI, which can separate proteins and peptides based on the difference of their pIs. In IEF, commercially available immobilized pH gradient (IPG) strips or the one-dimensional vertical IEF gel with gradient pH will be employed, and the latter can analyze multiple samples in a simpler and less time-consuming way compared to IPG strips. As for cIEF, it shortens the analysis time and minimizes consumption of smaples. The samples will first mixed with precise isoelectric point makers, ampholytes and stablilizers before loaded to the capillary. And the pI of protein samples can be detected in situ once the focusing is completed in the capillary. Two methods are available at Creative Proteomics for pI determination and our experiences scientists will optimize the protocols according to your special requirements and sample types.

Advantages of Isoelectric Point (pI) Determination Service:

  • Rich experience in pI determination.
  • High sensitivity and accuracy to detect proteins with different post-translational modifications.
  • Rapid Turnaround Time: 7-10 days to provide comprehensive report.
  • Customized service: according to you sample type and sample size, optimized protocols will be deployed.

Creative Proteomics's experts can provide our customers with a precise pI determination for proteins and peptides samples. You can choose the technique for pI determination or discuss with our scientists. Clear and concise written reports including protocols and customized services will be offered during drug development.

Want to learn more about isoelectric point determination or protein analysis service? Please contact us.


  • Righetti P.G. Determination of the isoelectric point of proteins by capillary isoelectric focusing. J. Chromatogr. A 1037 (2004) 491–4992.
  • Ganapathy-Kanniappan S. (2019). pI Dtermination of Native Proteins In Biological Samples. Current Protocols in Protein Science, e85. doi: 10.1002/cpps.85.

*For Research Use Only. Not for use in the treatment or diagnosis of disease.

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