Photoreactive Fab-Binding Domains for Site-Specific Antibody Conjugation
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Solution Overview
Problem
There is a need for site-selective conjugation of antibody-binding domains and antigen-binding fragments that do not interfere with the photo-crosslinking of photoreactive antibody binding domains to the Fc domain, and for improved compositions and methods for imaging, diagnosing, and treating diseases using site-specifically conjugated immunoglobulin Fab domains.
Innovation Solution
Development of photoreactive antibody-binding domains (pAbBDs) that specifically bind and crosslink to the Fab region of immunoglobulins, including variants of Protein A and Protein L domains with amino acid modifications at specific sites, allowing for site-specific photo-crosslinking and conjugation with immunoglobulins from various hosts, enabling covalent labeling and functionalization with desirable biological or chemical moieties.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Manufacturing precision
If photoreactive antibody-binding domains are used to bind to the Fc region of immunoglobulin, then covalent link formation is enabled upon UV light exposure, but site-selective conjugation to the Fab region is not achieved
Solution Approach 1:
The patent introduces photoreactive amino acid substitutions at specific positions (A28, G32, Q35, S36, N46, G49, E50, K53, or L54) within the Protein A domain D sequence to create localized photoreactive sites that specifically target the Fab region, enabling site-selective conjugation while maintaining binding specificity
Solution Approach 2:
The patent modifies the amino acid sequence of Protein A domain D by substituting specific residues with photoreactive amino acids, changing the chemical properties of the binding domain to enable photo-crosslinking capability while maintaining Fab region specificity
2Reliability
If amino acid modifications are introduced to enable photo-reactivity, then site-specific photo-crosslinking is achieved, but protein structure and binding affinity may be affected
Solution Approach 1:
The patent tests multiple photoreactive amino acid substitutions at different positions within the Protein A domain D sequence, identifying specific positions (A28, G32, Q35, S36, N46, G49, E50, K53, or L54) where photoreactive modifications achieve effective photo-crosslinking while maintaining acceptable protein structure and binding affinity
Solution Approach 2:
The patent systematically varies the amino acid sequence at specific positions to introduce photoreactive groups, optimizing the balance between photo-crosslinking efficiency and maintenance of protein structural integrity and binding function
3Manufacturing precision
If site-specific conjugation to Fab region is implemented, then interference with Fc domain photo-crosslinking is avoided, but conjugation complexity increases
Solution Approach 1:
The patent divides the immunoglobulin molecule into distinct target regions (Fab and Fc domains) and develops specialized binding domains that selectively target each region, allowing independent and simultaneous conjugation without interference between sites
Solution Approach 2:
The patent uses Protein A domain D as an intermediary binding domain that specifically recognizes and binds to the Fab region, facilitating site-specific conjugation while leaving the Fc region available for separate photo-crosslinking operations
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 pAbBDs enable site-specific and covalent immobilization of antibody fragments, facilitating efficient imaging and treatment of diseases by allowing simultaneous labeling of IgG and IgM with high conjugation efficiency and versatility across different hosts, while maintaining compatibility with standard protein expression and purification protocols.
Implementation Method 1
photoreactive antibody-binding domains (pAbBDs) that bind to the Fc region of immunoglobulin G (IgG) and that form a covalent link with native IgG upon exposure to non-damaging long-wavelength UV light
Data Source
AI summary
Provided is an adapter comprising an antibody binding domain (AbBD) that specifically binds and crosslinks to an immunoglobulin Fab region, where the AbBD is a variant of a Protein A domain D and has an amino acid replacement/modification at A28, G32, Q35, S36, N46, G49, E50, K53 or L54 of SEQ ID NO: 1 or combinations thereof, and where the AbBD is photoreactive. Also provided is an adapter comprising an AbBD that specifically binds and crosslinks to an IgG Fab region and/or to an immunoglobulin M (IgM) Fab region, where the AbBD is a variant of a Protein A domain D and has an amino acid replacement/modification at A28, E50, or L54 of SEQ ID NO: 1 or combinations thereof, where the AbBD is photoreactive. Provided is an adapter comprising an AbBD that specifically binds and crosslinks to an IgG Fab region, where the AbBD is a variant of a Protein L C* domain and has an amino acid replacement/modification at G22 or T46 of SEQ ID NO: 2 or a combination thereof, wherein the AbBD is photo-reactive. Methods for using the AbBD for imaging, diagnosing and/or treating a disease are provided.