Antibody Metal Ion Binding via DDD Motif
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Solution Overview
Problem
Current methods for generating metal ion binding proteins, such as antibodies or fragments, are inefficient in creating proteins where metal ions like Ca2+ bridge the interaction between the protein and its antigen, making the binding reversible upon metal ion presence or absence, which is crucial for specific applications.
Innovation Solution
Incorporating the amino acid sequence motif DDD within the light chain variable region's CDR1 and an additional D in CDR3 of the antibody, combined with a diverse set of heavy chain variable regions, to enhance the generation of metal ion-dependent binding proteins using phage display technology.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If conventional methods are used to generate metal ion binding proteins, then the generation process can proceed with standard antibody production techniques, but the hit rate of obtaining proteins with metal ion-dependent binding is very low
Solution Approach 1:
The patent introduces a specific amino acid motif (DDD or DxD) at a defined position (L35-L37 in CDR1) of the light chain variable region. This local structural modification creates a metal ion binding site with specific coordination geometry, transforming a conventional antibody structure into one capable of metal ion-dependent antigen binding. The localized change at the CDR1 region specifically enhances metal ion affinity without altering the overall antibody structure or other CDR regions.
Solution Approach 2:
The patent modifies the amino acid sequence parameters of the light chain variable region by incorporating specific aspartate-rich motifs (DDD or DxD) at predetermined positions. This parameter change alters the chemical properties of the antibody, specifically increasing its ability to coordinate metal ions like Ca2+ through the carboxylate groups of the aspartate residues. The modification changes the binding characteristics from conventional non-specific interaction to metal ion-dependent specific binding.
2Adaptability or versatility
If standard antibody generation methods are used, then the process can follow conventional protocols, but the resulting proteins lack controlled reversible binding through metal ion presence or absence
Solution Approach 1:
The patent incorporates the metal ion binding motif (DDD or DxD) into the light chain variable region during the antibody design phase, before the actual antigen binding function is required. This preliminary structural preparation ensures that the antibody is pre-configured with metal ion coordination capability, enabling subsequent controlled reversible binding without requiring additional modification steps or complex selection procedures.
Solution Approach 2:
The patent introduces metal ions (such as Ca2+) as intermediary molecules that mediate the binding between the antibody and antigen. The aspartate-rich motif in the light chain coordinates the metal ion, which then facilitates the binding interaction. This intermediary mechanism allows for controlled reversible binding, where the presence of metal ions promotes binding and their removal (via chelating agents) releases the antigen, providing temporal and conditional control over the binding event.
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
This approach significantly increases the hit rate of generating metal ion binding proteins that exhibit Ca2+ dependency, allowing for controlled binding and release from antigens using chelating agents like EDTA, enhancing their applicability in various biological and immunological applications.
Implementation Method 1
Incorporating the amino acid sequence motif DDD within the light chain variable region's CDR1 and an additional D in CDR3 of the antibody... significantly increases the hit rate of generating metal ion binding proteins that exhibit Ca2+ dependency
Implementation Method 2
allowing for controlled binding and release from antigens using chelating agents like EDTA
Data Source
AI summary
The present invention provides for a method for generating a metal ion binding protein, the method comprising a) integrating the amino acid sequence DDD into CDR1 of a light chain variable region of an antibody or fragment thereof; and b) combining the sequence of step a) with a heavy chain variable region of an antibody or fragment thereof; and c) isolating the protein. Also provided is the use of metal ion binding proteins generated by the method of the present invention for isolation and purification of proteins and for the reversible labeling of a target molecule. Also provided is a metal ion binding anti-CD8 protein.