Charge Variant Analysis of Trastuzumab under pH and Salt Gradients

Charge variants of proteins commonly result from post translational modifications (PTMs) during recombinant production. These PTMs, including C-terminal lysine clipping and glycosylation, result in acidic and basic charged residues relative to the native protein. The most common method to detect and assess acidic and basic variants is through ion-exchange chromatography (IEX), specifically weak cation-exchange (WCX). Trastuzumab, marketed under the trademark Herceptin^®, is a common monoclonal antibody in the biopharmaceutical industry. The determination of charge variants in trastuzumab is assessed on the bioZen 6 µm WCX column using both a pH and salt gradient.