Dimeric Peptide Inhibitors for PSD-95 Affinity and BBB Permeability
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Solution Overview
Problem
Current PSD-95 inhibitors, such as the Tat-NR2B9c peptide, have low affinity and selectivity for PDZ1-2 domains, limiting their therapeutic effectiveness in treating ischemic stroke, traumatic brain injury, and chronic pain conditions, and are associated with side effects due to non-specific NMDA receptor antagonism.
Innovation Solution
Development of dimeric peptide analogues linked by a PEG linker, with specific sequences and a Cell Penetrating Peptide (CPP) attached, that target PDZ1 and PDZ2 domains of PSD-95, enhancing affinity and stability, and allowing for improved blood-brain barrier permeability.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Reliability
If monomeric peptide inhibitors (e.g., Tat-NR2B9c) are used to target PSD-95, then they can penetrate the blood-brain barrier, but they exhibit low affinity and selectivity for PDZ1-2 domains
Solution Approach 1:
The inhibitor is divided into distinct functional segments: a dimeric peptide core containing two PDZ-binding motifs (each recognizing PDZ1 or PDZ2 domains) and a separate CPP moiety (e.g., Tat peptide) responsible for blood-brain barrier penetration. This segmentation allows optimization of affinity through the dimeric core while maintaining permeability through the attached CPP
Solution Approach 2:
The invention merges two previously separate functions into a single hybrid molecule: the high-affinity dimeric peptide inhibitor (providing specific binding to PDZ1-2) and the cell-penetrating peptide (providing blood-brain barrier permeability). The CPP is covalently attached to the dimeric peptide via a linker, creating a unified therapeutic agent that achieves both high affinity and brain penetration
2Reliability
If dimeric peptide analogues are developed to increase affinity for PDZ1-2 domains, then binding strength improves, but molecular size and complexity increase
Solution Approach 1:
The dimeric structure is constructed by joining two identical or similar peptide motifs (e.g., two copies of the NR2B9c sequence) through a flexible linker. Each motif independently binds to a PDZ domain, and the modular design allows systematic optimization of affinity while maintaining a relatively simple overall structure that can be synthesized using standard peptide chemistry techniques
3Reliability
If NMDA receptor antagonists are used to reduce excitotoxicity, then neuroprotection is achieved, but physiological important processes are prevented and side effects occur
Solution Approach 1:
The invention extracts and targets only the specific pathological interaction between PSD-95 and NMDA receptors that mediates excitotoxicity. By designing inhibitors that bind specifically to the PDZ domains of PSD-95 (particularly PDZ1 and PDZ2), the therapy disrupts the harmful nNOS/PSD-95/NMDA receptor complex formation without blocking the broader NMDA receptor functions that are physiologically important, thereby achieving neuroprotection with reduced side effects
Data Source
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AI summary
The invention provides novel potent inhibitors of the ternary protein complex of nNOS, PSD-95, and the NMDA receptor and pharmaceutical compositions comprising the inhibitors for prophylaxis and/or treatment of excitotoxic-related disease and chronic pain conditions in a subject. The inhibitors are dimeric PSD-95 inhibitors comprising a first peptide or peptide analogue linked to a second peptide or peptide analogue by a linker, wherein the first and the second peptide or peptide analogue comprise at least four amide-bonded residues having a sequence YTXV or YSXV, wherein a. Y is selected from among E, Q, and A, or an analogue thereof, and b. X is selected from among A, Q, D, N, N-Me-A, N-Me-Q, N-Me-D, and N-Me-N or an analogue thereof, and wherein a Cell Penetrating Peptide (CPP) is linked to the linker or to an amino acid side chain of the first and second peptide or peptide analogue. The linker can be a PEG or NPEG linker.