FGF-1 Mutants Enhancing Stability via Local Residue Substitution
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Solution Overview
Problem
Human fibroblast growth factor-1 (FGF-1) exhibits structural weaknesses at its N- and C-termini regions, leading to instability and reduced mitogenic potency, which limits its therapeutic applications and storage stability.
Innovation Solution
Mutations at positions 12 and 134, substituting residues with cysteine, valine, or threonine, enhance the stability and mitogenic activity of FGF-1 by increasing van der Waals contacts and cooperativity of unfolding, potentially eliminating the need for heparin in formulations and extending shelf-life.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If wild-type FGF1 is used, then the protein maintains its natural sequence and structure, but it exhibits structural weaknesses at N- and C-termini leading to instability and reduced mitogenic potency
Solution Approach 1:
The patent applies local quality by introducing specific mutations at positions 12 and 134 in the FGF1 sequence. These localized changes substitute residues with cysteine, valine, or threonine to enhance stability and mitogenic activity without altering the entire protein structure. The mutations target specific weak regions (N- and C-termini) to improve overall protein reliability.
Solution Approach 2:
The patent employs parameter changes by modifying the amino acid sequence parameters at critical positions. The substitutions (K12C, K12V, K12T, P134C, P134V, P134T) change the physical-chemical properties of the protein, increasing van der Waals contacts and cooperativity of unfolding, thereby enhancing thermal stability and mitogenic potency.
2Duration of action of stationary object
If mutations are introduced to enhance stability and mitogenic activity, then the protein exhibits improved therapeutic properties and longer shelf-life, but the sequence complexity increases
Solution Approach 1:
The patent minimizes sequence complexity by applying local quality changes only at positions 12 and 134. These targeted mutations extend shelf-life and enhance stability without requiring complex modifications throughout the entire 140-residue sequence, maintaining simplicity in production and characterization.
Solution Approach 2:
The patent achieves multi-functionality with the mutant FGF1 polypeptides that simultaneously provide enhanced thermal stability, extended shelf-life, increased mitogenic potency, and reduced aggregation. The same mutations (at positions 12 and 134) confer multiple beneficial properties, eliminating the need for separate modifications for each function.
3Reliability
If heparin is added to FGF1 formulations to stabilize the protein, then stability is improved, but the formulation complexity and potential side effects increase
Solution Approach 1:
The patent applies self-service by engineering the FGF1 protein itself to provide inherent stability through mutations at positions 12 and 134. The mutant polypeptides maintain stability and mitogenic activity without requiring external stabilizers like heparin, simplifying formulations and eliminating associated side effects while the protein serves its own stabilization needs.
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 FGF-1 polypeptides demonstrate increased stability and mitogenic potency, allowing for smaller dosages and potentially longer functional half-life, with Val mutations at positions 12 and 134 showing a 30-fold increase in mitogenic activity and substantial thermal stability.
Implementation Method 1
Val mutations within the N- and C-termini β-strands are shown to stabilize the structure and to increase van der Waals contacts by filling local cavities present within this region.
Implementation Method 2
The N- and C-termini β-strands hydrogen bond to each other
Data Source
AI summary
Mutants of human FGF-1 are disclosed having increased stability and mitogenic potency. In the FGF-1 polypeptide, primarily residue 12 is substituted with threonine and/or residue 134 is substituted cysteine, valine or threonine to render the polypeptide more stable and/or to increase its mitogenecity.