Ankyrin Repeat Binding Proteins for CD32a Specificity
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Solution Overview
Problem
Current methods lack a reliable and specific means to differentiate and target CD32a-positive cells from a mixture containing CD32b-positive cells, as existing antibodies often bind to both subtypes, and there is a need for proteins that can selectively recognize CD32a on the cell surface.
Innovation Solution
Development of binding proteins comprising ankyrin repeat domains with specific amino acid sequences that selectively bind to CD32a, allowing for the discrimination and identification of CD32a-positive cells without prior depletion of CD32b-positive cells, using sequences such as those found in SEQ ID NO: 28, 29, and 30, with up to 10 amino acid substitutions.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Measurement precision
If conventional antibodies are used to detect CD32a, then CD32a can be targeted, but CD32b cross-reactivity occurs making specific differentiation impossible
Solution Approach 1:
The invention applies local quality by designing ankyrin repeat domains with specific amino acid sequences that recognize and bind to unique local structural features of the CD32a extracellular domain. The binding proteins are engineered to interact with specific epitopes on CD32a that are structurally distinct from CD32b, enabling selective recognition at the molecular level despite overall sequence homology.
Solution Approach 2:
The invention employs parameter changes by systematically varying amino acid residues within the ankyrin repeat domain sequences to optimize binding affinity and specificity for CD32a. Through iterative sequence optimization and selection, the binding proteins achieve enhanced discrimination between CD32a and CD32b by fine-tuning the molecular recognition parameters of the protein-protein interaction interface.
2Stability of the object's composition
If CD32a and CD32b have high sequence homology, then structural similarity is maintained, but specific differentiation becomes extremely difficult
Solution Approach 1:
The invention applies segmentation by dividing the CD32a extracellular domain into distinct structural epitopes that can be selectively recognized. The ankyrin repeat domains are designed to bind to specific segmented regions or conformational epitopes on CD32a that differ from CD32b, allowing differentiation through targeted recognition of discrete structural elements rather than requiring overall sequence divergence.
3Measurement precision
If sequential magnetic bead cell-sorting is used to isolate CD32a-positive cells, then CD32a cells can be separated, but the process is extremely complex and time-consuming
Solution Approach 1:
The invention extracts the essential binding function from complex multi-step sorting procedures by creating standalone ankyrin repeat domain binding proteins that specifically recognize CD32a. These simplified binding proteins can be directly conjugated to detection or sorting reagents, eliminating the need for complex sequential magnetic bead procedures while maintaining the ability to specifically isolate and identify CD32a-positive cell subsets.
4Quantity of substance
If existing CD32a antibodies are used, then some CD32a binding is achieved, but validation for cell surface specificity is lacking
Solution Approach 1:
The invention applies self-service by designing ankyrin repeat domain binding proteins whose cell surface binding capability is inherently determined by their specific amino acid sequences and structural features. The binding proteins are engineered to naturally recognize and bind to the extracellular domain of CD32a on the cell surface, with their specificity and functionality being self-evident through their molecular design and validated through direct binding assays without requiring additional validation steps.
Data Source
AI summary
The present invention relates to binding proteins comprising ankyrin repeats, in particular such that specifically bind CD32a or specifically target CD32a positive cells. Nucleic acids encoding such binding proteins, nucleic acids, vectors comprising said nucleic acids, particles comprising said binding protein, a host cell comprising said nucleic acid, a pharmaceutical composition are disclosed and any of these for use in medicine and/or several gene therapies.