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Rationale: Conjugation sites are a quality attribute of conjugate vaccines. Proteolysis of bioconjugates synthesized by maleimide-thiol chemistry generates type 2 peptides with a hydrolyzed thiosuccinimide linker containing information on the conjugation sites. A mass spectrometry (MS)-cleavable linker could make the identification of conjugation sites by MS more reliable.
Methods: Four synthetic type 2 peptides with a hydrolyzed thiosuccinimide linker were analyzed by matrix-assisted laser desorption ionization (MALDI) MS/MS with and without collision gas. These peptides were also partially labeled with O in the linker to confirm the proposed fragmentation mechanism. A conjugate vaccine with the hydrolyzed thiosuccinimide linker was reduced and S-alkylated, digested with trypsin and analyzed by liquid chromatography-MS/MS using collision-induced dissociation (CID) and higher-energy collisional dissociation (HCD) fragmentation methods at a normalized collision energy of 30.
Results: A metastable fragmentation preferentially cleaves the newly formed pseudopeptide bond within the hydrolyzed thiosuccinimide linker of type 2 peptides to yield P + 71 and C + 98 ions. These ions make the assignment of conjugation sites more reliable. Partial O-labeling and MS/MS analysis confirmed the proposed structures. CID produces these ions as the two most intense signals more favorably than HCD. The latter also yields these ions, guarantees better sequence coverage and promotes other fragmentations in the linker.
Conclusions: Hydrolyzed thiosuccinimide linker is cleavable in MALDI and electrospray ionization MS/MS analysis by a gas-phase metastable fragmentation. The resulting fragment ions (P + 71 and C + 98) make the identification of conjugation sites more reliable. These results could be extended to self-hydrolyzing maleimides, which efficiently stabilize the thiosuccinimide linker upon hydrolysis, in antibody-drug conjugates.
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http://dx.doi.org/10.1002/rcm.9859 | DOI Listing |
Anal Chem
March 2025
Integrated Bioanalysis, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, South San Francisco, California 94080, United States.
Research into antibody-drug conjugates (ADCs) is currently at an inflection point due to recent clinical impact. ADC biotransformation analysis is key for understanding the structural integrity of ADCs in vivo and is a critical aspect of drug development, especially at the lead selection stage. Data analysis of biotansformed products is hindered by the manual and time-consuming analyte identification process oftentimes taking days to weeks.
View Article and Find Full Text PDFACS Pharmacol Transl Sci
January 2025
Integrated Bioanalysis, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, 121 Oyster Point Blvd, South San Francisco, California 94080, United States.
Antibody-drug conjugates (ADCs) are a promising drug modality substantially expanding in both the discovery space and clinical development. Assessing the biotransformation of ADCs and is important in understanding their stability and pharmacokinetic properties. We previously reported biotransformation pathways for the anti-B7H4 topoisomerase I inhibitor ADC, AZD8205, puxitatug samrotecan, that underpin its structural stability using an intact protein liquid chromatography-high resolution mass spectrometry (LC-HRMS) approach.
View Article and Find Full Text PDFAnal Chem
October 2024
Integrated Bioanalysis, Clinical Pharmacology and Safety Sciences, R&D, AstraZeneca, South San Francisco, California 94080, United States.
What happens to macromolecules ? What drives the structure-activity relationship and stability for antibody-drug conjugates (ADCs)? These interrelated questions are increasingly relevant due to the re-emerging importance of ADCs as an impactful therapeutic modality and the gaps that exist in our understanding of ADC structural determinants that underlie ADC stability. Complex macromolecules, such as ADCs, may undergo changes due to their intricate structure as biotransformations may occur on the linker, the payload, and/or at the modified conjugation site. Furthermore, the dissection of ADC metabolism presents a substantial analytical challenge due to the difficulty in the identification or quantification of minor changes on a large macromolecule.
View Article and Find Full Text PDFRapid Commun Mass Spectrom
December 2024
Integrated Bioanalysis, Clinical Pharmacology & Safety Sciences, R&D, AstraZeneca, South San Francisco, California, USA.
Rationale: Isomerism can be an important aspect in pharmaceutical drug development. Identification of isomers can provide insights into drug pharmacology and contribute to better design of drug molecules. The general approaches to differentiate isomers include Fourier-transform infrared spectroscopy (FTIR), nuclear magnetic resonance (NMR), and circular dichroism.
View Article and Find Full Text PDFRapid Commun Mass Spectrom
September 2024
Carlos Chagas Institute/FioCruz Rua Professor Algacyr Munhoz Mader, Curitiba, Brazil.