In running two-dimensional gel electrophoresis on bacterial protein, some spots that appear to match a protein sequence have a significantly more acidic isoelectric point than the calculated pI. Will post-translational modifications have this effect to this degree?
Dear Amanda Stock
give a look to the following paper
https://pubmed.ncbi.nlm.nih.gov/20690144/#:~:text=Glycosylation%20is%20the%20most%20common,the%20pI%20of%20a%20protein.
and the following link
https://www.protpi.ch/blog/bioinformatics/2015/01/isoelectric-point-and-molecular-mass-calculator-for-glycosylated-proteins/
that provide you a possible tool
https://www.protpi.ch/Calculator/ProteinTool
that seems to be able to predict the pI of the glicosilated and non glicosilated protien
best
Manuele
Yes, post-translational modifications can cause deviations between the observed isoelectric point (pI) and the calculated pI of a protein. The calculated pI is typically determined based on the amino acid sequence of the protein, assuming no modifications. However, PTMs can alter the protein's net charge and, consequently, its pI. For instance, phosphorylation adds negatively charged phosphate groups, lowering the pI, while acetylation can neutralize positive charges, potentially increasing the pI. Glycosylation and other modifications like methylation or ubiquitination can also affect the protein's charge and, consequently, its pI. Here are few references:
https://academic.oup.com/bioinformatics/article/28/22/2905/240075
https://academic.oup.com/bioinformatics/article/32/6/821/1744386
Article Shift in the isoelectric-point of milk proteins as a consequ...
Hope it helps!
Hi Amanda Stock
As others have mentioned, yes post-translational modifications can significantly affect protein pI.
If you're performing proteomic work using 2D electrophoresis, our SameSpots software might be of use to you to highlight significant changes in protein expression, you can access a free trial of the software here: https://totallab.com/products/samespots/
Best wishes,
Steven
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