Routine Peptide Map Characterization of Therapeutic Monoclonal Antibodies via LC/MS: Identification and Origin of Low-level Acetaldehyde-Modified Peptides

摘要

1. Low-level peaks detected during Lys-C peptide mapping were determined to be caused by acetaldehyde Schiff base modifications at the NH_2-termini of most major peptides. 2. These extra peaks were elucidated through accurate mass determinations and methodically traced to the reduction and alkylation reagents. (1) Reagent age (6-12 months old) was determined as the primary cause for the presence of acetaldehyde; (2) Occurs when using older batches of BOTH TCEP and IAA. 3. An expiration date of 6 months is recommended for TCEP and IAA to avoid this method-related artifact.