Patent ID: 6875594

Claim:
A method of cleaving a recombinantly expressed protein bound to an intein-chitin binding domain (CBD) and ligating said cleaved recombinant protein to a peptide containing an N-terminal cysteine having an unoxidized sulfhydryl side chain said method comprising contacting said recombinatly expressed protein bound to said intein-CBD with said peptide in a reaction solution containing a conjugated thiol, thereby effecting, in a one-pot reaction, cleavage of said recombinatly expressed protein from said intein-CBD and production of a C-terminal thioester of the recombinatly expressed protein which spontaneously undergoes intramolecular rearrangement to form an amide bond linking the C-terminus of said protein to the N-terminus of said peptide, wherein said conjugated thiol is selected from the group consisting of thiophenol, 2-nitrothiophenol, 2-thiobenzoic acid, 2-thiopyridine, 4-thio-2-pyridine carboxylic acid and 4-thio-2-nitropyridine.