Activated cysteine-directed polypeptide ligation technique
Embodiments of the present disclosure pertain to methods of conjugating a molecule to a polypeptide by (1) modifying one or more thiol residues on the polypeptide, where the modifying includes cyanylation of the one or more thiol residues; and (2) associating the polypeptide with the molecule, where the associating results in the conjugation of the molecule to the polypeptide through a reaction between a nucleophilic moiety on the molecule and the one or more modified thiol residues. The cyanylation may include attachment of cyano groups to sulfur atoms of the one or more thiol residues to form thiocyanato groups that undergo reversible intramolecular addition with a nearby N-amide group to generate a 1-acyl-2-iminothiazolidine intermediate. Thereafter, the nucleophilic moiety on the molecule reacts with the 1-acyl-2-iminothiazolidine intermediate to replace 2-iminothiazolidine in a nucleophilic acyl substitution reaction and result in the conjugation of the molecule to the polypeptide.
1 . A method of conjugating a molecule to a polypeptide, said method comprising:
modifying one or more thiol residues on the polypeptide, wherein the modifying comprises cyanylation of the one or more thiol residues, and wherein the one or more thiol residues are part of one or more thiol-containing non-canonical amino acids on the polypeptide; and
associating the polypeptide with the molecule, wherein the associating results in the conjugation of the molecule to the polypeptide through a reaction between a nucleophilic moiety on the molecule and the one or more modified thiol residues.
2 . The method of claim 1 , wherein the cyanylation comprises attachment of cyano groups to sulfur atoms of the one or more thiol residues to form thiocyanato groups, and wherein the thiocyanato groups undergo reversible intramolecular addition with a nearby N-amide group to generate a 1-acyl-2-iminothiazolidine intermediate.
3 . The method of claim 2 , wherein the nearby N-amide group is a cysteine N-amide.
4 . The method of claim 2 , wherein the attachment comprises associating the polypeptide with a reagent comprising the cyano groups.
5 . The method of claim 4 , wherein the reagent is 2-nitro-5-thiocyanatobenzoic acid (NTCB).
6 . The method of claim 2 , wherein the nucleophilic moiety on the molecule reacts with the 1-acyl-2-iminothiazolidine intermediate to replace 2-iminothiazolidine in a nucleophilic acyl substitution reaction and result in the conjugation of the molecule to the polypeptide.
7 . The method of claim 1 , wherein the associating comprises mixing the polypeptide with the molecule.
8 . The method of claim 1 , wherein the associating occurs at a time selected from the group consisting of before, during, and after the modifying step.
9 . The method of claim 1 , wherein the polypeptide comprises at least one of a peptide or a protein.
10 . The method of claim 1 , wherein the one or more thiol residues are located at the C-terminus of the polypeptide but not the last amino acid at the C-terminus.
11 . The method of claim 1 , wherein the polypeptide comprises one or more non-canonical amino acids.
12 . The method of claim 1 , wherein the one or more thiol residues are part of one or more cysteines on the polypeptide.
13 . The method of claim 1 , wherein the molecule is selected from the group consisting of small molecules, macromolecules, lipids, oligonucleotides, peptides, polypeptides, proteins, polyethylene glycols, fluorophores, chromophores, and combinations thereof.
14 . The method of claim 1 , wherein the molecule comprises a peptide.
15 . The method of claim 1 , wherein the nucleophilic moiety is an amine group.
16 . The method of claim 15 , wherein the amine group is selected from the group consisting of hydrazine, primary amines, secondary amines, hydrazine, hydrazides, hydroxylamines, O-alkylhydroxylamines, ammonia, and combinations thereof.
17 . The method of claim 1 , wherein the method does not require enzymatic catalysis.
18 . The method of claim 1 , wherein the polypeptide is selected from the group consisting of ubiquitin (Ub), ubiquitin-like proteins (Ubls), SUMO1, SUMO2, SUMO3, SUMO4, ISG15, FAT10, MNSF beta, UFM1, ATG12, URM1, HUB1, GABARAP, GABARAPL2, and combinations thereof.
19 . The method of claim 1 , wherein the molecule is a therapeutic peptide selected from the group consisting of exenatide, human calcitonin, salmon calcitonin, enfuvirtide, bivalirudin, teriparatide, thymosin alpha, liraglutide, lixisenatide, dulaglutide, semaglutide, taspoglutide, pexiganan, histone H2A, RNAse H, and combinations thereof.