Histidine-Covalent Stapled Alpha-Helical Peptides Targeting hMcl-1

Area of Science:

• Medicinal Chemistry
• Chemical Biology
• Drug Discovery

Background:

• Covalent drugs targeting cysteine (Cys) residues are clinically effective, but druggable Cys sites are limited.
• There is a need for novel covalent drug strategies targeting other amino acid residues.
• Histidine (His) residues are frequently located in protein binding sites and possess desirable nucleophilicity, yet are underutilized targets for covalent ligands.

Purpose of the Study:

• To design and characterize novel stapled peptides for covalent targeting of histidine (His) residues.
• To explore the potential of His-targeting covalent ligands for therapeutic applications.
• To investigate the covalent modification of hMcl-1 at the His 252 residue.

Main Methods:

• Rational design of stapled peptides.
• In vitro biochemical assays.
• Nuclear Magnetic Resonance (NMR) spectroscopy.
• X-ray crystallography.
• Cellular assays for characterization.

Main Results:

• Successful design and synthesis of novel stapled peptides targeting His 252 of hMcl-1.
• In vitro and cellular characterization confirmed the covalent modification of the target His residue.
• Structural and biochemical data validated the covalent binding mechanism.

Conclusions:

• The study validates the potential of using electrophiles for the specific covalent targeting of histidine (His) residues.
• This work expands the scope of covalent drug design beyond traditional Cys-targeting agents.
• The developed His-targeting stapled peptides represent a promising new class of covalent inhibitors.