Single-chain Fc polypeptide univalent binding
Find Innovative SolutionsGenerate Solutions
Solution Overview
Problem
Current methods for producing univalent antibody fragments are impractical due to low yields and complex procedures, such as proteolytic cleavage or hybrid protein dimerization, which hinder large-scale production and efficient targeting of cell surface antigens without causing co-stimulation or antigenic modulation.
Innovation Solution
A single-chain polypeptide comprising two CH2 and two CH3 domains that form a functional Fc domain within the chain, linked by suitable amino acid sequences, allowing for recombinant production and monovalent binding without dimerization, enabling efficient targeting and effector functions like complement fixation and receptor binding.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If proteolytic cleavage is used to produce univalent antibody fragments, then the fragments retain natural effector functions, but the production yield is low and the procedure is complex
Solution Approach 1:
The antibody molecule is segmented into separate domains (Fc and variable regions) that are genetically fused to create a single-chain polypeptide. This segmentation allows the Fc domain to be separated from the need for proteolytic processing while retaining effector functions, and enables direct recombinant expression of the functional fragment without complex cleavage procedures.
Solution Approach 2:
A linker peptide acts as an intermediary element connecting the Fc domain to the variable region in the single-chain polypeptide. This intermediary allows the two functional domains to be genetically fused while maintaining their individual functions, eliminating the need for proteolytic cleavage and enabling high-yield recombinant production.
2Strength
If bivalent antibodies are used for targeting cell surface antigens, then binding affinity is enhanced, but co-stimulation and antigenic modulation occur causing cell evasion
Solution Approach 1:
The variable region responsible for antigen binding is extracted and genetically fused to the Fc domain in a single-chain configuration. This extraction creates a univalent binding structure that maintains affinity while preventing the cross-linking and co-stimulation effects caused by bivalent antibodies, thereby eliminating cell evasion mechanisms.
Solution Approach 2:
Instead of using the traditional bivalent antibody structure with two separate Fab arms, the invention inverts the approach by creating a single-chain polypeptide with a single variable region fused to Fc. This inversion changes the valency from bivalent to univalent, preventing harmful co-stimulation while maintaining target binding capability.
3Reliability
If univalent antibody fragments are produced by traditional methods, then antigenic modulation is avoided, but the production process is costly and time-consuming
Solution Approach 1:
The Fc domain and variable region are preliminarily connected through genetic fusion to form a single-chain polypeptide that is directly expressed as a functional univalent fragment. This preliminary action eliminates the need for subsequent proteolytic cleavage and purification steps, dramatically reducing preparation time and cost while maintaining the univalent structure that avoids antigenic modulation.
Solution Approach 2:
The single-chain polypeptide is designed to self-assemble into the functional univalent fragment structure through its intrinsic domain architecture. The Fc domain and variable region automatically fold and function together without requiring external proteolytic processing, enabling direct recombinant production and eliminating time-consuming preparation steps.
Data Source
Figure 1a~1c
Figure 2a~2c
Figure 3a~3c
AI summary
The present invention relates to single chain polypeptides comprising one or more immunoglobulin Fc domains. In particular the present invention relates to single-chain Fc polypeptides in which at least one functional Fc domain is formed within the polypeptide chain.