Cleavage Cocktail for Peptides Containing Arg Residues (Reagent R)

Cleavage Cocktail for Peptides Containing Arg Residues (Reagent R)

 Reagent R is especially suited for cleaving and deprotecting peptides that contain arginine residues protected with sulfonyl protecting groups. This reagent also is recommended for tryptophan-containing peptides prepared on PAL or BAL resin, for it minimizes reattachment of the peptide to the linker at the tryptophan residue.

Preparation of Reagent R

Combine trifluoroacetic acid (TFA, 90% v/v), thioanisole (5% v/v), 1,2-ethanedithiol (3% v/v), and anisole (2% v/v). Use immediately.

Cleavage and Deprotection with Reagent R 

1. If necessary, remove Fmoc-protecting groups using the standard Fmoc removal procedure. 

2. Suspend the resin in Reagent R (10 mL/g of peptide resin). 

3. Allow the mixture to stand at room temperature for 2 hours. 

4. Filter the resin. 

5. Wash the resin with Reagent R (2 x 5 mL /g resin). 

6. Combine the filtrates and add cold ether to precipitate the crude peptide. 

Peptides containing multiple Arg residues may need additional deprotection time to fully deprotect all of the Arg residues.