Cystine Knot Peptide Scaffold for Stable VEGF-A Binding
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Solution Overview
Problem
There is a need for small, stable, artificial antibody-like molecules for therapeutic and diagnostic applications, particularly for ocular diseases and disorders, with high thermal stability and the ability to bind to vascular endothelial growth factor A (VEGF-A).
Innovation Solution
Development of non-naturally occurring cystine knot peptides (CKPs) with specific amino acid sequences that bind to VEGF-A, exhibiting high thermal stability, resistance to proteolytic degradation, and the ability to inhibit VEGF-A activity with an IC50 between 0.5 nM and 1.0 nM, and are capable of binding to human, mouse, and rat VEGF-A.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Stability of the object's composition
If conventional protein scaffolds are used, then they can perform biological functions, but they lack sufficient thermal stability and proteolytic resistance
Solution Approach 1:
The patent combines multiple stabilizing elements into a composite protein scaffold structure: disulfide bridges (Cys residues), salt bridges (Arg-Glu pairs), and alpha-helix promoting mutations are integrated together to create a scaffold that simultaneously achieves thermal stability and proteolytic resistance. The cystine knot topology with its three disulfide bonds forms a composite structural framework that resists both thermal denaturation and proteolytic degradation.
Solution Approach 2:
The patent systematically modifies amino acid parameters to enhance stability: introducing disulfide bridges changes the chemical bonding parameters, adding salt bridges alters electrostatic interactions, and mutating residues to increase alpha-helix propensity changes secondary structure parameters. These parameter changes collectively improve both thermal stability and proteolytic resistance.
2Length of moving object
If protein size is reduced for better tissue penetration, then diagnostic and therapeutic efficacy improves, but structural stability decreases
Solution Approach 1:
The patent divides the large antibody structure into a smaller, simplified scaffold platform that retains essential binding functions. The engineered protein scaffold is segmented into specific structural elements (beta-sheets, alpha-helices, disulfide bridges) that provide stability without requiring the full antibody size, enabling better tissue penetration while maintaining structural integrity.
Solution Approach 2:
The patent extracts and isolates only the essential stabilizing elements from full antibody structures, creating a minimal scaffold platform. By taking out the core stabilizing features (disulfide bridges, salt bridges, helical regions) and removing non-essential portions, the design achieves small size with enhanced stability per unit mass.
3Reliability
If multiple mutations are introduced to enhance stability and binding, then therapeutic efficacy improves, but protein folding and expression complexity increases
Solution Approach 1:
The patent applies mutations locally at specific positions rather than throughout the entire protein sequence. Disulfide bridges are placed at specific cysteine positions, salt bridges at specific arginine-glutamate pairs, and alpha-helix mutations at specific residues. This localized approach enhances binding affinity and stability while minimizing overall folding complexity.
Solution Approach 2:
The patent designs a universal scaffold platform where a single set of stabilizing mutations serves multiple functions: disulfide bridges provide both structural stability and proteolytic resistance, salt bridges contribute to both thermal stability and binding affinity, and alpha-helix mutations enhance both fold stability and ligand interaction. This multi-functionality reduces the need for separate stabilization elements.
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 CKPs effectively inhibit VEGF-A activity and are resistant to trypsin digestion, offering potential therapeutic applications for ocular diseases characterized by angiogenesis and vascular permeability, with effective delivery systems such as ocular implants.
Implementation Method 1
They are roughly 30-50 amino acids in length and contain six conserved cysteine residues which form three disulfide bonds
Implementation Method 2
The unique arrangement of the disulfide bonds renders cystine-knot peptides highly stable to thermal, proteolytic and chemical degradation
Implementation Method 3
The unique arrangement of the disulfide bonds renders cystine-knot peptides highly stable to thermal, proteolytic and chemical degradation
Data Source
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AI summary
Provided are non-naturally occurring cystine knot peptides (CKPs) that bind to VEGF-A. Additionally, provided are methods of using non-naturally occurring CKPs that bind to VEGF-A, including diagnostic and therapeutic compositions and methods. Non-naturally CKPs that bind low density lipoprotein receptor-related protein 6 (LRP6) are also provided.