Isolation and quantification of N-glycans from immunoglobulin G antibodies for quantitative glycosylation analysis

Abstract

N-glycosylation is one of the critical quality attributes for the therapeutic monoclonal antibodies. Characterization of N-glycans of monoclonal antibodies provides valuable information about its therapeutic efficacy. We present a non-invasive method of isolating N-glycans from Immunoglobulin G based antibodies for glycosylation analysis. The method consists of purification of antibodies from biological solution and release of N-glycans with peptide-N-glycosidase F in a single consolidated process using a mini affinity ligand column (e.g. protein-A column). The method is highly reproducible with average coefficient of variation of 0.012 in the glycoform percentage distributions between the replicates. The method provides quantification of the molar yield of glycans as a function of molar concentration of antibody in a single analysis. To our knowledge, this is the first time this approach was used to detect and quantify any macro-heterogeneity of N-glycosylation in monoclonal antibody samples. This fairly rapid and very cost-efficient method would be of great interest for academic labs and biopharmaceutical industries.