Toward Precision Bioconjugation: Chemical Strategies for Site-Selective Cysteine Conjugation.

Area of Science:

• Chemical Biology
• Biochemistry
• Materials Science

Background:

• Precision engineering of peptides and proteins is crucial for understanding molecular functions and developing new therapeutics and biomaterials.
• Chemoselective bioconjugation techniques allow modification of specific amino acid side chains.
• Site-selective modification offers ultimate control over linkage type and conjugation position in peptides and proteins.

Purpose of the Study:

• To review chemical strategies for site-selective modification of cysteine residues in peptides and proteins.
• To provide guidance for future synthetic developments in precision chemistry.
• To highlight the evolution of site-selective protein modification as a tool for rational design of biomolecules.

Main Methods:

• Focus on chemoselective transformations targeting cysteine residues.
• Exploitation of the local cysteine environment, including neighboring functional groups (e.g., α-amine, carboxylate).
• Utilizing temporary interactions with proximal amines for site-selectivity, even for internal cysteines.

Main Results:

• Cysteine residues, with their nucleophilic thiols, are ideal targets for chemoselective modification.
• Strategies leveraging neighboring groups enable selective N- or C-terminal modifications.
• New methods allow differentiation between internal cysteines, enhancing site-selectivity.

Conclusions:

• Site-selective protein modification is a powerful tool for designing and controlling complex biomolecules.
• These advancements redefine possibilities in chemical biology, therapeutics, and biomaterials science.
• User-friendly approaches like TriTEx will accelerate the adoption of precision biomolecule conjugates.