Cyclic Peptide Binders Targeting K-Ras G12D via Epitope Tagging
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Solution Overview
Problem
Current attempts to develop Ras inhibitors, particularly for the K-Ras G12D oncogenic protein, have been unsuccessful due to difficulties in outcompeting GTP for the binding pocket and the lack of known allosteric regulatory sites.
Innovation Solution
Development of cyclic peptides that selectively bind to the K-Ras G12D protein using click chemistry, with specific sequences and linkers to target the oncogenic epitope, allowing for selective inhibition of the K-Ras G12D oncoprotein.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If conventional Ras inhibitors are designed to compete with GTP for the K-Ras binding pocket, then binding affinity to K-Ras may be improved, but the ability to outcompete GTP in cellular conditions deteriorates
Solution Approach 1:
The patent uses an epitope tag (FLAG sequence) as an intermediary to enable selective binding. The cyclic peptides do not compete directly with GTP for the native K-Ras binding pocket but instead bind to the engineered epitope tag on K-Ras, allowing selective inhibition without direct competition with GTP
Solution Approach 2:
The invention introduces localized modifications to K-Ras by adding a specific epitope tag at a defined location (N-terminus or internal position). This local modification creates a new binding site that preserves the native K-Ras function while enabling selective peptide binding to the tagged region
2Stability of the object's composition
If the K-Ras protein structure is left unchanged, then native K-Ras function is preserved, but the ability to develop selective inhibitors deteriorates due to lack of known allosteric regulatory sites
Solution Approach 1:
The patent applies preliminary action by introducing the epitope tag into the K-Ras protein sequence before inhibitor development. This pre-modification creates a defined binding target that enables subsequent selective peptide binding while maintaining native function
Solution Approach 2:
The epitope tag serves as an intermediary element that bridges the native K-Ras protein and the cyclic peptide inhibitors. It provides a new interaction surface without disrupting the native protein structure or function
3Reliability
If cyclic peptides are designed with specific sequences and linkers to target K-Ras G12D epitope, then selectivity for G12D mutant is improved, but the complexity of peptide design and synthesis increases
Solution Approach 1:
The cyclic peptide is divided into distinct functional segments: a recognition element that binds the G12D-specific epitope, a linker region that provides structural flexibility, and a detection group. This segmentation allows systematic optimization of each component independently
Solution Approach 2:
The patent systematically varies peptide parameters including amino acid sequence, cyclic linker composition, and detection group type to optimize binding affinity and selectivity. This parameter-based approach enables rational design while managing complexity
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 cyclic peptides effectively bind to and inhibit the K-Ras G12D protein, demonstrating strong affinity and selectivity, with some variants showing EC50 binding values as low as 33.3 μM, and inducing proteasomal degradation of the protein in cancer cells.
Implementation Method 1
cyclic peptides that selectively bind to the K-Ras G12D protein using click chemistry
Implementation Method 2
inducing proteasomal degradation of the protein in cancer cells
Data Source
AI summary
Cyclic peptides represented by (Formula 1)selectively bind the oncoprotein K-Ras G12D in vitro and in cellulo, where Z1 and Z2 are each L-propargylglycine (Pm), azidoornithine (OrnN3), or L-azidolysine (Az4), and V1-V2-V3-V4-V5 is an amino acid variable region having a sequence selected from the group consisting of SEQ ID NOs: 1-20.