Chimeric Uricase Reduces Immunogenicity While Maintaining Enzymatic Activity
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Solution Overview
Problem
Current treatments for hyperuricemia and gout, such as allopurinol, have limitations including chronic side effects and inability to cure gouty deposition, and recombinant uricases like Aspergillus flavus uricase induce severe immunogenic reactions due to low homology with human uricase, limiting long-term treatment efficacy.
Innovation Solution
A humanized recombinant uricase is developed by combining amino acids from dog uricase and human uricase, with specific mutations and truncations to enhance stability and reduce immunogenicity, encoded by a DNA sequence and expressed in a host cell for use in treating hyperuricemia and gout.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If Aspergillus flavus uricase is used to treat hyperuricemia, then uric acid conversion efficacy is improved, but immunogenicity increases causing severe allergic reactions
Solution Approach 1:
The patent applies local quality by creating a chimeric uricase protein that combines specific regions from different species: the catalytic domain from Aspergillus flavus uricase (maintaining high enzymatic activity) and the C-terminal region from human uricase (reducing immunogenicity). This localized combination allows the protein to maintain functional efficacy while reducing harmful immune responses.
Solution Approach 2:
The invention uses composite materials principle by constructing a chimeric protein composed of amino acid sequences from different sources. The N-terminal portion (residues 1-239) is derived from Aspergillus flavus uricase for catalytic function, while the C-terminal portion (residues 240-304) is derived from human uricase to reduce immunogenicity, creating a composite protein with optimized properties.
2Productivity
If conventional uricosuric agents are used to promote uric acid excretion, then uric acid elimination is improved, but kidney function requirement increases making them invalid for reduced kidney function
Solution Approach 1:
Instead of promoting uric acid excretion through the kidneys (the conventional approach that fails in kidney impairment), the invention inverts the strategy by directly converting uric acid to allantoin in the bloodstream through enzymatic action. This alternative pathway bypasses the kidney excretion mechanism, making the treatment effective even when kidney function is reduced.
3Reliability
If allopurinol is used to inhibit xanthine oxidase, then uric acid synthesis is reduced, but chronic side effects occur including neutropenia and liver dysfunction
Solution Approach 1:
Rather than inhibiting uric acid synthesis upstream (which causes chronic side effects with long-term use), the invention converts the harmful approach into a beneficial one by directly addressing the accumulated uric acid through enzymatic conversion to allantoin. This transforms the problem from preventing uric acid formation to safely eliminating existing uric acid, avoiding the chronic toxic effects of synthesis inhibition.
4Object-affected harmful factors
If human uricase gene is used, then immunogenicity is reduced, but enzymatic activity is lost due to terminator codon mutation
Solution Approach 1:
The patent applies local quality by selectively using different regions from different species: the functional catalytic domain from Aspergillus flavus uricase that maintains enzymatic activity, and the immunologically tolerant C-terminal region from human uricase. This localized combination resolves the contradiction between activity and immunogenicity.
Solution Approach 2:
The chimeric structure acts as an intermediary between fully fungal uricase (high activity, high immunogenicity) and fully human uricase (low immunogenicity, no activity). By combining regions from both sources, the invention creates an intermediate protein that mediates between these two extremes, achieving both activity and reduced immunogenicity.
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 chimeric uricase maintains enzymatic activity while increasing identity with human uricase, reducing immunogenicity and improving stability, allowing for effective long-term treatment of hyperuricemia and gout with enhanced physical and chemical properties.
Implementation Method 1
Uricase (EC 1.7.3.3) exists extensively in microorganisms (such as Bacillus fastidiosus, Candida mycoderma and Aspergillus flavus), plants (such as beans and chickpeas), and animals (such as pigs, cows, dogs, and papios) (Suzuki K et al., J. Biosci. Bioeng., 2004, 98: 153-158). It can catalyse the oxidation of uric acid to allantoin at the presence of oxygen, releasing carbon dioxide
Implementation Method 2
Uricase (EC 1.7.3.3) exists extensively in microorganisms (such as Bacillus fastidiosus, Candida mycoderma and Aspergillus flavus), plants (such as beans and chickpeas), and animals (such as pigs, cows, dogs, and papios) (Suzuki K et al., J. Biosci. Bioeng., 2004, 98: 153-158). It can catalyse the oxidation of uric acid to allantoin at the presence of oxygen, releasing carbon dioxide
Data Source
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AI summary
The present invention provides a humanized recombinant uricase and mutants thereof, wherein the humanized recombinant uricase is a chimeric protein which comprises amino acids of non-human mammal uricase and amino acids of human uricase. The humanized recombinant uricase and mutants thereof have reduced immunogenicity in human, and can be used for the treatment of hyperuricemia and gout.