title: Accurate determination of succinimide degradation products using high fidelity trypsin digestion peptide map analysis.
abstract: We report an efficient, high fidelity trypsin digestion method for peptide map analysis. This method minimizes artifacts caused by the sample preparation process, and we show its utility for the accurate determination of succinimide formation in a degraded monoclonal antibody product. A basic charge variant was detected by imaged capillary isoelectric focusing and was shown with reduced antigen binding and biological activity. Samples were reduced under denaturing conditions at pH 5.0, and digestion of the reduced protein with porcine trypsin was performed at pH 7.0 for 1 h. Following reversed phase high-performance liquid chromatography and online mass spectrometric analysis, succinimide formation was identified at Asp30 in the light chain. This result contrasts with the observation of only iso-Asp and Asp residues under conventional sample preparation conditions, which are therefore concluded to be artificially generated. The Asp30 residue is seen in the cocrystal structure model to participate in favorable charge interaction with an antigen molecule. Formation of succinimide and the resulting loss of negative charge are therefore hypothesized to be the degradation mechanism. After treatment of the degraded antibody sample to mildly alkaline pH conditions, we observed only Asp residue as the succinimide hydrolysis product and concurrent recovery of biological activity.
authors.affiliation: Protein Analytical Chemistry and Biological Technologies, Genentech, a Member of the Roche Group, South San Francisco, California 94080-4990, United States. yu.c@gene.com
authors.forename: X Christopher
authors.initials: XC
authors.lastname: Yu
authors.forename: Koman
authors.initials: K
authors.lastname: Joe
authors.forename: Yu
authors.initials: Y
authors.lastname: Zhang
authors.forename: Andrea
authors.initials: A
authors.lastname: Adriano
authors.forename: Yaning
authors.initials: Y
authors.lastname: Wang
authors.forename: Helene
authors.initials: H
authors.lastname: Gazzano-Santoro
authors.forename: Rodney G
authors.initials: RG
authors.lastname: Keck
authors.forename: Galahad
authors.initials: G
authors.lastname: Deperalta
authors.forename: Victor
authors.initials: V
authors.lastname: Ling
mesh_terms: D000818:Animals; D000911:Antibodies, Monoclonal / Q000235:genetics / Q000378:metabolism; D002851:Chromatography, High Pressure Liquid / Q000379:methods; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D007525:Isoelectric Focusing / Q000379:methods; D013058:Mass Spectrometry / Q000379:methods; D010449:Peptide Mapping / Q000379:methods*; D011994:Recombinant Proteins / Q000235:genetics / Q000378:metabolism; D013388:Succinimides / Q000032:analysis*; D013552:Swine; D014357:Trypsin / Q000378:metabolism*
chemical_list: D000911:Antibodies, Monoclonal; D011994:Recombinant Proteins; D013388:Succinimides; C032620:succinimide; D014357:Trypsin