Abstract: Methods of producing cyclic peptides and splicing intermediates of peptides in a looped conformation are disclosed. The methods utilize the trans-splicing ability of split inteins to catalyze cyclization of peptides from a precursor peptide having a target peptide interposed between two portions of a split intein. The interaction of the two portions of the split intein creates a catalytically-active intein and also forces the target peptide into a loop configuration that stabilizes the ester isomer of the amino acid at the junction between one of the intein portions and the target peptide. A heteroatom from the other intein portion then reacts with the ester to form a cyclic ester intermediate. The active intein catalyzes the formation of an aminosuccinimide that liberates a cyclized form of the target peptide, which spontaneously rearranges to form the thermodynamically favored backbone cyclic peptide product.

Abstract: Methods of producing cyclic peptides and splicing intermediates of peptides in a looped conformation are disclosed. The methods utilize the trans-splicing ability of split inteins to catalyze cyclization of peptides from a precursor peptide having a target peptide interposed between two portions of a split intein. The interaction of the two portions of the split intein creates a catalytically-active intein and also forces the target peptide into a loop configuration that stabilizes the ester isomer of the amino acid at the junction between one of the intein portions and the target peptide. A heteroatom from the other intein portion then reacts with the ester to form a cyclic ester intermediate. The active intein catalyzes the formation of an aminosuccinimide that liberates a cyclized form of the target peptide, which spontaneously rearranges to form the thermodynamically favored backbone cyclic peptide product.