Chondroitinase ABCI Mutants for Spinal Cord Injury
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Solution Overview
Problem
Spinal cord injuries often result in permanent paralysis due to the inability of neurons to regenerate across the glial scar formed after injury, primarily because chondroitin sulfate proteoglycans (CSPGs) inhibit nerve tissue growth.
Innovation Solution
Development of mutant chondroitinase ABCI enzymes with enhanced activity and resistance to inactivation, which can degrade CSPGs, facilitating neuronal regeneration and neurological functional recovery by modifying access to extravascular spaces and reducing inflammation.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild type chondroitinase ABCI is used to degrade CSPGs, then neuronal regeneration is promoted, but the enzyme is rapidly inactivated by UV or heat exposure
Solution Approach 1:
The patent applies parameter changes by modifying the amino acid sequence of chondroitinase ABCI through site-directed mutagenesis. Specific residues (e.g., Tyr105, His108, Glu174, Lys177) are mutated to alter the enzyme's physical-chemical properties, enhancing its resistance to UV radiation and heat inactivation while preserving its CSPG-degrading activity. This allows the enzyme to maintain functionality under therapeutic conditions.
Solution Approach 2:
The patent creates multiple mutant variants (055D2-3, 079B6-2, 023G6-4, 005B12-3) with different stability profiles. These mutants can be selected and used based on specific therapeutic requirements, replacing the wild type enzyme which has limited stability. The mutants are designed to be more durable for in vivo applications where the enzyme would otherwise be rapidly inactivated.
2Productivity
If chondroitinase ABCI is administered to degrade CSPGs, then neurological functional recovery is promoted, but the enzyme activity is insufficient due to rapid inactivation
Solution Approach 1:
The patent modifies kinetic and stability parameters of chondroitinase ABCI through amino acid substitution. The mutant enzymes exhibit enhanced resistance to inactivation by UV radiation and heat, allowing them to maintain catalytic activity for longer periods in the inflammatory and oxidative environment following spinal cord injury, thereby sustaining neuronal regeneration-promoting effects.
Solution Approach 2:
The patent performs preliminary stabilization of the enzyme through mutagenesis before in vivo administration. The mutant enzymes are pre-adapted to withstand harsh conditions (UV exposure, heat) that would otherwise inactivate the wild type enzyme during storage, delivery, and therapeutic action, ensuring adequate activity is maintained when administered to promote neuronal regeneration.
3Object-generated harmful factors
If wild type chondroitinase ABCI is used therapeutically, then CSPG degradation occurs, but the enzyme cannot withstand the inflammatory environment after spinal cord injury
Solution Approach 1:
The patent converts the harmful effect of UV radiation and heat (which normally inactivate the enzyme) into a selection criterion for creating more robust mutants. By exposing enzyme variants to these stressors and selecting survivors, the patent creates chondroitinase ABCI mutants that are specifically adapted to withstand the inflammatory, oxidative, and thermal environment following spinal cord injury, turning previously harmful conditions into a means of enhancing enzyme resilience.
Solution Approach 2:
The patent alters the physical-chemical parameters of chondroitinase ABCI through amino acid substitution to enhance its tolerance to UV radiation and heat. Specific mutations (e.g., at positions 105, 108, 174, 177) modify the enzyme's structure to increase its stability and resistance to denaturation under the harsh conditions present in injured spinal cord tissue, allowing it to effectively degrade CSPGs despite the harmful environment.
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 chondroitinase ABCI enzymes effectively promote neuronal outgrowth, regeneration, and neurological functional recovery by degrading CSPGs, thereby overcoming growth inhibition and reducing inflammation, potentially leading to restored motor, sensory, and autonomic functions.
Implementation Method 1
The mutant chondroitinase ABCI enzymes effectively promote neuronal outgrowth, regeneration, and neurological functional recovery by degrading CSPGs
Data Source
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AI summary
The present invention relates to protein and nucleic acid mutants of chondroitinase ABCI. Such chondroitinase ABCI mutant enzymes exhibit altered chondroitin lyase activity or increased resistance to inactivation from stressors including UV light or heat. Methods of using chondroitinase ABCI mutant enzymes are also provided.