Mutant Streptavidin Reducing Immunogenicity While Retaining Biotin Affinity
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Solution Overview
Problem
The high immunogenicity of streptavidin derived from Streptomyces avidinii in human bodies leads to early generation of anti-streptavidin antibodies, hindering the practical application of pretargeting methods in drug delivery and diagnostics, as existing mutant streptavidins with reduced immunogenicity compromise biotin binding affinity.
Innovation Solution
A mutant streptavidin is developed by introducing specific amino acid mutations, such as substituting arginine at position 72 with lysine, tyrosine at position 10 with serine or threonine, tyrosine at position 71 with alanine or serine, glutamic acid at position 89 with aspartic acid, arginine at position 91 with lysine, and glutamic acid at position 104 with glutamine or asparagine, to reduce immunogenicity while maintaining strong biotin binding affinity.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If amino acid mutations are introduced to reduce immunogenicity of streptavidin, then immunogenicity decreases, but biotin binding affinity becomes very low
Solution Approach 1:
The patent applies parameter changes by systematically varying amino acid residues at specific positions (10, 71, 89, 91, 104) to find the optimal balance between reduced immunogenicity and maintained biotin binding affinity. Multiple mutant variants were created with different amino acid substitutions to optimize these parameters.
Solution Approach 2:
The patent applies local quality by making targeted amino acid substitutions at specific positions (10, 71, 89, 91, 104) rather than throughout the entire protein. This allows localized modification of immunogenic regions while preserving the overall structure and biotin binding capability of the streptavidin molecule.
2Reliability
If wild-type streptavidin is used in pretargeting method, then high biotin binding affinity is achieved, but anti-streptavidin antibody is generated early preventing practical use
Solution Approach 1:
The patent modifies the wild-type streptavidin by changing amino acid parameters at specific positions to reduce immunogenicity while attempting to maintain biotin binding affinity, creating a new protein variant suitable for in vivo applications.
Solution Approach 2:
The patent converts the harmful immunogenicity of wild-type streptavidin into a benefit by using the knowledge of antigenic determinants to strategically modify immunogenic regions, thereby reducing antibody generation while preserving the useful biotin binding function.
Data Source
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AI summary
It is an object of the present invention to provide a mutant streptavidin wherein the immunogenicity (antigenicity) in mammals of a streptavidin is reduced. The present invention provides a mutant streptavidin, which comprises an amino acid sequence in which (a) the arginine residue at position 72 is substituted with another amino acid residue, and (b) any one or more of the tyrosine residue at position 10, the tyrosine residue at position 71, the glutamic acid residue at position 89, the arginine residue at position 91, and the glutamic acid residue at position 104 are substituted with other amino acid residues, with respect to the amino acid sequence of a core streptavidin as shown in SEQ ID NO: 2, and which has decreased immunogenicity as compared with that of a wild-type streptavidin.