Patent ID: 7872096

Claim:
A method comprising: native chemical ligating a first isolated intein domain D 1 and a second isolated intein domain D 2 to-polymer X (n) in a cell-free system to produce a compound comprising the structure: D 1 -X (n) -D 2 wherein: polymer X (n) comprises n residues of a monomer X, wherein n is at least 2, and polymer X (n) is not made up of only naturally-occurring amino acid monomers; said compound comprises a first intein reactive site at the N-terminus of polymer X (n) ; said compound comprises a second intein reactive site at the N-terminus of D 2 ; and said compound produces a cyclic product comprising said polymer, wherein said cyclic product is cyclized via a reaction that joins said first intein reactive site and said second intein reactive site.