Articles tagged ”SEC-MS”

Unravelling Structural Conformers within a Therapeutic Multispecific mAb using FabALACTICA

Scientists at the University of Strasbourg and Sanofi describe the global structural characterisation of a trispecific antibody which exhibits two distinct structural isoforms when analyzed by size-exclusion chromatography (SEC). FabALACTICA proved to be a valuable tool in this study as above hinge digestion of this trispecific antibody allowed for middle-level characterisation of the isomeric Fab regions and facilitated cyclic-ion mobility (cIM) differentiation of the isomers, which was not possible in the intact molecule without prior SEC separation.
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Analytical Methods to Monitor Site-Specific ADC Generation with GlyCLICK®

Scientists at the University of Strasbourg and University of Geneva use innovative native MS and IM methodologies for analytical characterization of a site-specific ADC generated with the GlyCLICK technology.


Antibody-drug conjugates (ADCs) combine the benefits of tumor-targeting monoclonal antibodies with the cytotoxic effect of drug payloads covalently linked to the antibody. The ADC generation process has evolved from non-selective and uncontrolled conjugation in early generation products, to site-specific conjugation resulting in homogenous and well-defined ADCs. Conjugation at the antibody Fc glycan sites using the GlyCLICK technology has proven to be an attractive option for the generation of site-specific ADCs.
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Using FabALACTICA® to Elucidate Proline Trans-cis Isomerization on a Trispecific Antibody

January 30, 2020 | References |
FabALACTICA digestion

FabALACTICA digestion above hinge of a trispecific anti-HIV antibody (Masiero et al 2020).

Proline isomerization can occur in the antigen binding complementary determining regions (CDRs) of an antibody and impact the interaction with the antibody target. In this paper, scientists at Sanofi in Vitry-sur-Seine, France, found an unusual size exclusion chromatography profile of a trispecific anti-HIV antibody and determined that the heterogeneity originated from a proline isomerization.


Peptide bonds are planar due to the partial double bond character of the C-N bond and typically occur in a trans conformation since the cis confirmation is energetically unfavorable. However, proline with its ring structure, has a significantly lower energetic threshold and cis conformers occur more frequently as observed in crystal structures. The proline trans-cis isomerization plays various roles in biology where it can act as a molecular switch in immune function and cell signaling but it also plays a role in pathologies such as cancer and Alzheimer’s disease.


Scientists at Sanofi in Vitry-sur-Seine, France, found an unusual size exclusion profile of a trispecific anti-HIV antibody and determined that the heterogeneity originates from a proline isomerization.  In this paper,  Masiero et al., studied a trispecific antibody carrying three variable domains that displayed two non-resolved peaks in a UHPLC-SEC analysis. In combination with mass spectrometry, identical masses for the two peaks were observed. To dissect the origin of the heterogeneity, FabALACTICA was used to digest the antibody above the hinge and generate three fragments; an intact Fc fragment, a Fab fragment binding one antigen and a second Fab fragment with two antigen binding domains. Due to the specificity of FabALACTICA, the fragments could be analyzed using SEC-MS with high accuracy and the origin of the double peak was attributed to the domain with two antigen binding domains.


In summary, proline trans-cis isomerization can occur in the CDRs of antibodies and impact the analytical profile of the antibody. The complexity of multispecific antibodies can be reduced using specific enzymatic tools such as FabALACTICA for more detailed analysis.


  1. Masiero, A. et al., 2020. The impact of proline isomerization on antigen binding and the analytical profile of a trispecific anti-HIV antibody. mAbs, 12(1), p.1698128.


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