Isoelectric point (pI) and exctinction coefficients (ε) are basic phys-chem properties that are widely used to assist peptide design, separation and purification. There are many tools that allow calculation of pI and ε using natural amino-acid sequence as the input. Unfortunately, these methods exclude the nonatural amino acids and thus are incorrect for modified and conjugated peptides. We fill this gap by introducing a robust method that allows pI calculation using the peptide’s 2D chemical structure instead of the sequeunce. Ionization of the non-natural side chains or conjugated groups are predicted on the fly and are included into the pI calculation in addition to the set of predefined pKa’s of natural side chains. The method is validated on experimental data of 29 compounds, providing improvement of R<sup>2</sup> from 0.74 to 0.96 over the conventional sequence-based approach. It is available at http://peptide-tools.com free web server together with the conventional sequence-based ε estimators. The corresponsding python code is free and open-source: https://github.com/AstraZeneca/peptide-tools. It is easy, quick, and robust - just provide your structure file, SMILES, sequence and get the predictions.

Peptide-tools.com – web server for phys-chem properties prediction for natural and modified peptides

Fall 2022 abstracts, posters, and presentations will launch in mid-September.

ACS Fall 2022

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.