Method to convert N-terminal glutamine to pyroglutamate for characterization of recombinant monoclonal antibodies

Cyclization of N-terminal glutamine to pyroglutamate is a common modification of recombinant monoclonal antibodies that has often been identified by liquid chromatography mass spectrometry (LC-MS) analysis using separated fractions. An alternative approach of using glutaminyl-peptide cyclotransferase to convert the N-terminal glutamine to pyroglutamate was developed in the current study. Enzymatic conversion of the N-terminal glutamine to pyroglutamate not only provides an identification of the N-terminal amino acids without fraction collection but also can significantly simplify the chromatograms to assist fraction collections for the characterization of other antibody variants. (C) 2013 Elsevier Inc. All rights reserved.