Characterization of nonenzymatic glycation on a monoclonal antibody.

We present here an improved analytical method for the analysis of glycation events in proteins. Nonenzymatic glycation of an IgG2 monoclonal antibody was studied using affinity chromatography, mass spectrometry, and chemical derivatization. Analysis of both forced-degraded and bulk-drug substance (BDS) samples showed the presence of glycated protein. A new peptide mapping procedure, incorporating derivatization using sodium borohydride, allowed the development of a sensitive method for detecting and identifying the sites of modification. When combined with tandem mass spectrometry, peptides glycated by glucose showed dramatically improved MS/MS spectra as compared to underivatized controls. Using these methods we were able to map a number of glycation sites in both forced-degraded and BDS samples that were distributed across both light and heavy chain subdomains. The combination of affinity chromatography, high-resolution mass spectrometry, and a simple derivatization procedure should allow the facile analysis of glycation for other antibody and protein samples.