BiTE® Polypeptide Preparation with Sequential Protease Digestion
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Solution Overview
Problem
Existing methods for mass spectrometric analysis of bi-specific T-cell engager (BiTE®) molecules, such as those containing conserved α-CD3 domains and linker peptides, face challenges due to cleavage resistance and non-specific digestion by trypsin, leading to difficulties in monitoring modifications and quantitation of critical attributes like deamidation and isomerization sites, which impact potency and safety.
Innovation Solution
A novel method involving sequential digestion with a first protease followed by neutrophil elastase to generate specific fragments, allowing for improved analysis of BiTE® molecules, including denaturation, reduction, and alkylation steps, and using 30 kDa MWCO filters to enhance specificity and retention of linker peptides.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If trypsin digestion is used for peptide mapping and MAM, then digestion specificity and frequency of lysine and arginine residues are improved, but the ability to monitor modifications in CDR domains is worsened due to cleavage resistance
Solution Approach 1:
The patent applies segmentation by using a two-step digestion process: first with trypsin to cleave at lysine and arginine residues, then with neutrophil elastase to further cleave the resulting peptides at different sites. This segmented approach generates a comprehensive set of overlapping peptides that cover regions resistant to single enzyme digestion, enabling monitoring of modifications in CDR domains while maintaining the advantages of trypsin specificity.
2Manufacturing precision
If trypsin digestion is used, then basic residues on C-terminus are produced with optimal length for mass spectrometry, but large size of linker peptide prevents effective analysis
Solution Approach 1:
The patent segments the large linker peptide (approximately 8 kDa) by applying sequential digestion with trypsin followed by neutrophil elastase. This breaks down the large peptide into smaller fragments that are suitable for mass spectrometry analysis, chromatographic separation, and detection, while still covering the entire region including CDR domains.
Solution Approach 2:
The patent performs preliminary trypsin digestion before neutrophil elastase digestion. This preliminary action creates intermediate peptides that are more accessible to neutrophil elastase cleavage sites, ensuring comprehensive coverage of the linker region and optimizing the final peptide size distribution for analysis.
3Adaptability or versatility
If secondary proteases such as Asp-N, Lys-C, and Glu-C are used, then alternative cleavage sites are provided, but the linker region still has no residues susceptible to these enzymes
Solution Approach 1:
The patent uses trypsin as an intermediary enzyme in a sequential digestion process. Trypsin first cleaves at lysine and arginine residues, creating intermediate peptides that expose new cleavage sites for neutrophil elastase. This intermediary action enables subsequent neutrophil elastase digestion to access and cleave at sites within the linker region that are not susceptible to Asp-N, Lys-C, or Glu-C enzymes alone.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The method enables robust characterization and quantitation of critical attributes in BiTE® molecules, reducing non-specific cleavage and improving chromatographic separation and mass spectrometry data interpretation.
Implementation Method 1
the at least two fragments of the polypeptide are subsequently digested by a neutrophil elastase
Implementation Method 2
using 30 kDa MWCO filters to enhance specificity and retention of linker peptides
Implementation Method 3
including denaturation, reduction, and alkylation steps
Implementation Method 4
including denaturation, reduction, and alkylation steps
Data Source
AI summary
The disclosed methods are directed to preparing and detecting polypeptides using neutrophil elastase, such as human neutrophil elastase. The polypeptides are optionally denatured, reduced, and/or alkylated before being subjected to a first digestion. A second digestion comprises the use of neutrophil elastase, such as human neutrophil elastase. The prepared fragments are then analyzed chromatographically, electrophoretically, or spectrometrically, or a combination of these methods. The methods are especially useful for the preparation of therapeutic polypeptides for analysis, especially those that are not easily cleaved, such as some bi-specific T-cell engager (BiTE®) molecules.