Nitrite-assisted peptide iodination and conjugation.

Area of Science:

• Biochemistry
• Organic Chemistry
• Chemical Biology

Background:

• Selective modification of peptides and proteins is crucial for various biological applications.
• Existing methods for iodination can lack specificity or require harsh conditions.

Purpose of the Study:

• To establish a simple and selective method for iodinating peptides and proteins.
• To explore the utility of nitrite as a catalyst in peptide and protein modification.

Main Methods:

• Utilized angiotensin II as a model peptide system.
• Investigated nitrite-catalyzed iodination in acidic solutions.
• Examined the alkylation of N-terminal-iodinated peptides with thiol-containing molecules in basic solutions.
• Analyzed the effect of pH on the reaction between sodium nitrite and sodium iodide for selective iodination at tyrosine and histidine residues.

Main Results:

• Demonstrated selective N-terminal iodination of peptides catalyzed by nitrite in acidic conditions.
• Showcased the formation of peptide conjugates through alkylation of N-terminal-iodinated peptides with thiol-containing molecules (e.g., N-acetylcysteine, glutathione) in basic conditions.
• Identified that increasing the pH from 4 to 8 of the sodium nitrite and sodium iodide reaction mixture leads to selective iodination of tyrosine and histidine residues in peptides and proteins.

Conclusions:

• Nitrite serves as an effective catalyst for selective iodination of peptides and proteins.
• The developed method offers a versatile approach for peptide and protein ligation.
• This technique provides a new tool for bioconjugation and modification of biomolecules.