Database of pre-computed isoelectric points and molecular weights for proteins and digest peptides from model organism proteomes (20,115 species)

The goals of the database include making statistical comparisons of the various prediction methods (21 algorithms implemented) as well as facilitating the biological investigation of protein isoelectric point space. The isoelectric point, the pH at which a particular molecule carries no net electrical charge, is an important parameter for many analytical biochemistry and proteomics techniques, especially for 2D gel electrophoresis (2D-PAGE), capillary isoelectric focusing (cIEF), liquid chromatography–mass spectrometry (LC-MS) and X-ray protein crystallography
2D plots of predicted molecular weight and isoelectric point can be useful for initial
identification of proteins in the sample and limiting the complexity of the further analysis

Protease digests (peptides with molecular weight and isoelectric point) can be
useful for bottom-up proteomics MS analysis

61,329,034 protein sequences from 20,115 proteomes with isoelectric point predicted using 21 algorithms

5.38 Billion dissociation constant (pKa) predictions for proteins

Proteomes in silico digested with the five most frequently used proteases (Trypsin, Chymotrypsin, Trypsin+LysC, LysN, ArgC)
In total, 9.58 Billion peptides


Check some of the most frequently used proteomes


If you are interested in the analysis of isoelectric point for proteins coming from all organisms use one of the files

Stats
Proteome-pI 2.0 is available under Creative Commons Attribution-NoDerivs license, for more details see here

Reference: Kozlowski LP. Proteome-pI 2.0: Proteome Isoelectric Point Database Update. Nucleic Acids Res. 2021, doi: 10.1093/nar/gkab944 Contact: Lukasz P. Kozlowski