Overexpression of recombinant proteins with a C‐terminal thiocarboxylate: Implications for protein semisynthesis and thiamin biosynthesis

A facile and rapid method for the production of protein C‐terminal thiocarboxylates on DNA‐encoded polypeptides is described. This method, which relies on the mechanism of the cleavage reaction of intein‐containing fusion proteins, can produce multi‐milligram quantities of protein C‐terminal thiocarboxylate quickly and inexpensively. The utility of this method for protein semisynthesis and implications for studies on the biosynthesis of thiamin are discussed.