Engineered Clostridial Toxins Isoelectric Point Modification
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Solution Overview
Problem
Clostridial toxin therapies face challenges with unwanted diffusion from the administration site, leading to undesirable side effects due to poor tissue retention, which can be life-threatening, especially at high doses or concentrations.
Innovation Solution
Engineered clostridial toxins with specific amino acid modifications that increase the isoelectric point, reducing diffusion and enhancing tissue retention without affecting target cell binding and SNARE protein cleavage capabilities.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Productivity
If high doses or concentrations of clostridial toxin are used to enhance therapeutic efficacy, then the therapeutic effect is improved, but unwanted diffusion from the administration site increases leading to life-threatening side effects
Solution Approach 1:
The patent applies parameter changes by modifying the isoelectric point (pI) of the clostridial toxin protein through amino acid substitutions. Specifically, acidic amino acids (aspartic acid, glutamic acid) are replaced with basic amino acids (lysine, arginine, histidine), shifting the pI from acidic/neutral to basic range (pI > 7). This parameter modification alters the toxin's electrostatic properties, enabling it to bind more strongly to negatively charged tissue components and resist diffusion, thereby allowing high therapeutic doses without increased side effects
2Stability of the object's composition
If amino acid modifications are made to increase isoelectric point and reduce diffusion, then tissue retention is improved, but the complexity of toxin engineering increases
Solution Approach 1:
The patent applies local quality by making targeted amino acid modifications at specific locations in the toxin protein sequence, rather than comprehensive redesign. The modifications are concentrated in the heavy chain region, specifically replacing acidic residues with basic residues at positions that do not interfere with the toxin's active sites or binding domains. This localized approach achieves the desired pI shift and tissue retention improvement while maintaining simplicity in the overall protein structure and function
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 engineered toxins demonstrate improved tissue retention and reduced side effects, allowing for higher doses or prolonged action with reduced adverse effects, thereby increasing therapeutic efficacy and safety.
Implementation Method 1
engineered clostridial toxins with specific amino acid modifications that increase the isoelectric point, reducing diffusion and enhancing tissue retention
Data Source
AI summary
The present invention provides engineered clostridial toxins comprising at least one amino acid modification, wherein said at least one amino acid modification increases the isoelectric point (pi) of the engineered clostridial toxin to a value that is at least 0.2 pi units higher than the pi of an otherwise identical clostridial toxin lacking said at least one amino acid modification, and wherein said at least one amino acid modification is not located in the clostridial toxin binding domain (Hc domain). Also provided are medical uses of the engineered clostridial toxins.