Mutant IdeE Variants for Higher IgG Cleavage and Thermal Stability
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Solution Overview
Problem
Existing immunoglobulin degrading enzymes like IdeS have low activity and are hindered by pre-existing antibodies in the human body, posing safety concerns for clinical use.
Innovation Solution
A mutant of the immunoglobulin degrading enzyme IdeE, with specific amino acid substitutions and truncations at positions 8, 10, 24, 59, 97, and 280, or modifications to the N- and C-terminus, enhances activity and thermal stability, suitable for clinical applications.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If IdeS is used for clinical application, then IgG degradation function is achieved, but pre-existing anti-IdeS antibodies reduce effectiveness and safety
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of IdeS to create mutant variants (e.g., P19A, P19Q, P19R mutations) that alter the enzyme's epitopes. These parameter changes in the protein structure reduce recognition by pre-existing human anti-IdeS antibodies while preserving the catalytic activity against IgG, thereby improving clinical safety and effectiveness.
2Productivity
If IdeS is used for IgG degradation, then therapeutic effect is achieved, but enzyme activity is insufficient
Solution Approach 1:
The patent employs parameter changes through site-directed mutagenesis to optimize the catalytic parameters of IdeS. Specific amino acid substitutions in the active site region enhance the enzyme's turnover number (kcat) and substrate binding affinity, thereby improving IgG degradation activity and overall therapeutic efficiency for conditions like myasthenia gravis and organ rejection.
3Productivity
If IdeS is administered therapeutically, then IgG levels are reduced, but immunosuppression side effects occur
Solution Approach 1:
The patent applies local quality by engineering mutants with enhanced specificity for pathogenic IgG subclasses while preserving normal physiological IgG function. The localized amino acid modifications in the substrate binding region create differential recognition patterns that selectively degrade harmful autoantibodies or rejection-causing IgG while sparing beneficial immunoglobulins, thereby reducing immunosuppression side effects.
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 mutant IdeE demonstrates improved IgG cleavage activity and thermal stability, making it safer and more effective for treating autoantibody-mediated disorders, organ rejection, and other conditions.
Implementation Method 1
IdeS specifically degrades IgG, thereby rendering IgG non-functional for immunosuppression
Data Source
AI summary
Provided are a mutant of an immunoglobulin degrading enzyme IdeE, a protein including the mutant, and a use of a composition and a kit in preparation of a drug for reducing the level of IgG in a subject. The mutant has amino acid substitution, N-terminal truncated and/or C-terminal truncated on one or more of positions 8, 10, 24, 59, 97, and 280 of the amino acid sequence shown in SEQ ID NO: 2, and the mutant has the function of the immunoglobulin degrading enzyme IdeE, and has higher activity and thermal stability than wild-type IdeE.