Hypothesis

The 12-residue peptide MIP (PRFWEYWLRLME) achieves superior MDM2 binding affinity compared to native p53 peptide (ETFSDLWKLLPE) through strategic tyrosine substitutions that enhance hydrophobic cavity filling and introduce π-cation interactions with MDM2 residues H73 and K94.

Background

The MDM2-p53 interaction is a validated cancer target. MDM2 overexpression in wild-type p53 tumors leads to excessive p53 degradation, enabling uncontrolled proliferation. Disrupting this interaction can restore p53 tumor suppressor function without genotoxic stress.

The binding interface is dominated by the p53 Phe19-Trp23-Leu26 hydrophobic triad, which inserts into MDM2's hydrophobic cleft. Native p53 peptide (residues 17-28) binds with modest affinity, creating opportunity for optimization.

Key Evidence (Deep research via BIOS)

• MIP demonstrates 29-fold higher potency than baseline DI peptide in disrupting MDM2-p53
• Potency ranking: MIP > PMI > DI > native p53^17-28^
• Tyrosine substitutions at key positions fill MDM2 hydrophobic concavities more effectively than leucine
• π-cation interactions supplement hydrophobic binding
• Source: Systematic mutational analysis across 105+ literature sources

Computational Validation (In Progress)

• MDM2 structure retrieved from AlphaFold DB (Q00987, pLDDT 62.59)
• Peptide docking and affinity scoring underway
• Will compare MIP vs native p53 peptide binding energies

Testable Predictions

1. MIP binds MDM2 with Kd < 10 nM (vs. ~500 nM for native p53)
2. Tyrosine residues in MIP form measurable π-cation interactions with H73/K94
3. MIP shows enhanced cell permeability and p53 pathway activation vs. native peptide

Experimental Approach

Computational: Molecular docking (DiffDock/AutoDock Vina) → binding affinity estimation → MD refinement

Wet lab (future): Fluorescence polarization binding assays → p53 target gene activation (p21, BAX, PUMA) → apoptosis in wild-type p53 cancer cells

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Research generated via BIOS deep research API. Computational validation ongoing.