Bjellqvist: calculated according to pKa and amino acid position.Cofactor: calculated with correction factors according to amino acid position and adjacent charged residues.Iterative: calculated from amino acid sequence.The researchers chose the following tools to undergo benchmarking: 1 The researchers benchmarked algorithm performance, comparing results obtained against public data sets to show how well these predictive tools performed. (2015) compared and contrasted five tools available to researchers for determining p I on the basis of amino acid sequence. Although these predictive methods exist, their performance can be variable and may skew ensuing results.Īudain et al. Various methods for predicting p I in denatured proteins exist, and most base this calculation on amino acid sequence with reference to p K a values recorded for ionizable constituents. p I depends on a number of factors, including amino acid sequence, post-translational modifications (PTMs) and presence of side chain-all of which can alter surface charge and behavior depending on the pH of the environment. This factor governs electrophoretic mobility in proteins and also plays a role in identifying peptides from mass spectral proteomics data. The isoelectric point, or p I,represents a point of balance for a molecule, where the external surface charge is a net zero.

Amino acid sequence