POLYPEPTIDE TERMINAL BINDERS AND USES THEREOF

1 . An engineered binder that specifically binds to an N-terminally modified target polypeptide modified by an N-terminal modifier agent, wherein:

(i) the N-terminally modified target polypeptide has a formula: M-P1-P2-polypeptide, wherein M is an N-terminal modification, P1-P2-polypeptide is a target polypeptide before modification with the N-terminal modifier agent, M-P1 is a modified N-terminal amino acid (NTAA) residue of the target polypeptide, and P2 is a penultimate terminal amino acid residue of the target polypeptide;

(ii) the engineered binder specifically binds to the N-terminally modified target polypeptide through interaction between the engineered binder and the M-P1 of the N-terminally modified target polypeptide; and

(iii) the engineered binder comprises an amino acid sequence having at least about 80% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 7—SEQ ID NO: 20.

2 . The engineered binder of claim 1 , wherein the N-terminal modification is a chemical entity having a volume from about 100 Å 3 to about 1000 Å 3 .

3 . The engineered binder of claim 1 , wherein the N-terminal modifier agent is selected from the group consisting of compounds of the following formula:

(A)

wherein R is CH 3 , CF 3 , OC(CH 3 ) 3 , or OCH 2 C 6 H 5 ,

and X is H, CH 3 , CF 3 , CF 2 H, or OCH 3 ;

(B)

wherein X is H, CH 3 , CF 3 , CF 2 H, OCH 3 , or SO 2 NH 2 ;

(C)

wherein X is H, F, Cl, OCH 3 , OCF 3 , CN, or SO 2 NH 2 ,

and LG is succinimide, pentafluorophenyl, or tetrafluorophenyl; and

(D)

wherein X is H, F, Cl, NH 2 , OCH 3 , OCF 3 , CN, or SO 2 NH 2 , A=CONH or SO 2 , G=0 or 1 CH 2 ,

R is any amino acid or unnatural amino acid, and

Z ring=0 (not there), 1, 2, or 3 CH 2 .

4 . The engineered binder of claim 1 , wherein the N-terminal modification (M) comprises an N-terminal blocking group and, optionally, a natural or unnatural amino acid moiety;

wherein the natural or unnatural amino acid moiety comprises a compound selected from the group consisting of: a naturally-occurring amino acid residue, 3-(3′-pyridyl)-L-alanine, L-cyclohexylglycine, α-aminoisobutyric acid, 3-(4′-pyridyl)-L-alanine, L-azetidine-2-carboxylic acid, isonipecotic acid, L-phenylglycine, β-(2-thienyl)-L-alanine, 3-(4-thiazolyl)-L-alanine, 1-aminocyclopentane-1-carboxylic acid, (2-trifluoromethyl)-L-Phenylalanine, L-cyclopropylalanine, 3-(2′-pyridyl)-L-alanine, beta-cyano-L-alanine, α-methyl-L-4-Fluorophenylalanine, α-methyl-D-4-fluorophenylalanine, 3-amino-2,2-difluoro-propionic acid, O-sulfo-L-tyrosine sodium salt, L-2-furylalanine, 1-aminocyclopropane-1-carboxylic acid, 3,5-dinitro-L-tyrosine, pentafluoro-L-phenylalanine, 3,5-difluoro-L-phenylalanine, 3-fluoro-L-phenylalanine, N-cyclopentylglycine, 1-(amino)cyclohexanecarboxylic acid, N-methylalanine, 4-amino-tetrahydropyran-4-carboxylic acid, 4-amino-1,1-dioxothiane-4-carboxylic acid, 4-amino-1-methyl-4-piperidinecarboxylic acid, 2-amino-N-(2,4-dimethoxybenzyl)acetamido)acetic acid, and a N-alkylated derivative thereof;

and the N-terminal blocking group comprises a compound selected from the group consisting of: 4-methylbenzoic acid, 4-(dimethylamio)benzoic acid, nicotinic acid, 3-aminonicotinic acid, 2-pyrazinecarbooxylic acid, 5-amino-2-fluoro-isonicotinic acid, 2,3-pyrazinedicarboxylic acid, 4,7-Difluoroisobenzofuran-1,3-dicarboxylic acid, 4-chloro-2-aminobenzoic acid, 4-nitro-2-aminobenzoic acid, 7-methoxy-1h-benzo[d][1,3]oxazine-2,4-dione, 4-carboxy-2-aminobenzoic acid, 6-(Trifluoromethyl)-2,4-dihydro-1h-3,1-benzoxazine-2,4-dione, 7-(Trifluoromethyl)-1h-benzo[d][1,3]oxazine-2,4-dione, 6-fluoro-2-aminobenzoic acid, 4-fluoro-2-aminobenzoic acid, 5-methoxy-2-aminobenzoic acid, 4-fluorobenzoic acid, 4-(trifluoromethyl)benzoic acid, 2-ethynyl fluorobenzaldehyde, 2-aminobenzoic acid, Succinic anhydride, 3,6-Difluoropyridine-2-carboxylic acid, 2-Fluoronicotinic acid, 5-Bromo-2-hydroxynicotinic acid, 4-(Trifluoromethyl)pyrimidine carboxylic acid, 2-Oxo-1,2-dihydropyridine-3-carboxylic acid, 5-Methyl-2-aminobenzoic acid, 6-Fluoropicolinic acid, 3-Methyl-2-aminobenzoic acid, 4-Methyl-2-aminobenzoic acid, 2-Amino methylbenzoic acid, 2-Amino-6-fluorobenzoic acid, 2-Amino-5-fluorobenzoic acid, 2-Amino-3-fluorobenzoic acid, 2-Amino-4-fluorobenzoic acid, 2-Aminonicotinic acid, 4-Aminonicotinic acid, 3-Aminopicolinic acid, 2-Amino-4,5-difluorobenzoic acid, 3,4-difluorobenzoic acid, 3,4,5-difluorobenzoic acid, 3-(Methoxycarbonyl)bicyclo[1.1.1]pentane-1-carboxylic acid, 3,3-Difluorocyclobutane-1-carboxylic acid, 1-Methyl-2-oxo-piperidine-4-carboxylic acid, Tetrahydropyran-4-carboxylic acid, 5-Fluoroorotic acid, 3-Fluoro-4-nitrobenzoic acid, 3-(Difluoromethyl)-1-methyl-1H-pyrazole-4-carboxylic acid, 4-(Difluoromethoxy)benzoic acid, 1-(Difluoromethyl)-1h-pyrazole-3-carboxylic acid, 4-(Methanesulfonylamino)benzoic acid, 5-Fluoro-6-methoxynicotinic acid, Tetrahydro-2H-thiopyran-4-carboxylic acid 1,1-dioxide, 4-(1H-Tetrazol-5-yl)benzoic acid, 1,2,3-Thiadiazole-4-carboxylic acid, 1,3-Benzodioxole-4-carboxylic acid, 2,1,3-Benzoxadiazole-5-carboxylic acid, 1-Benzyl-3-methyl-1h-pyrazole-5-carboxylic acid, 1-Cyclopropyl-6,7-difluoro-1,4-dihydro-4-oxoquinoline-3-carboxylic acid, 3,4-Dichlorobenzoic acid, 5-Fluoro-6-methylpyridine-2-carboxylic acid, 4,5-Dimethyl-2-(1h-pyrrol-1-yl)thiophene-3-carboxylic acid, 1,3-Dimethyl-1h-thieno[2,3-c]pyrazole-5-carboxylic acid, 1-[(4-Fluorobenzene)sulfonyl]piperidine-3-carboxylic acid, 1-(4-Fluorobenzyl)-5-oxopyrrolidine-3-carboxylic acid, 3-Fluoro-4-methoxybenzoic acid, 4-Fluoro-3-nitrobenzoic acid, 6-Fluoro-4-oxochromene-2-carboxylic acid, 3-Fluorophenylacetic acid, 4-Fluoro-3-(trifluoromethyl)benzoic acid, 5-Furan-2-yl-isoxazole-3-carboxylic acid, 1-Isopropyl-2-(trifluoromethyl)-1h-benzimidazole-5-carboxylic acid, Levofloxacin carboxylic acid, 3,5,7-Trifluoroadamantane-1-carboxylic acid, 3,4,5-Trimethoxybenzoic acid, 2-Oxo-2,3-dihydro-1h-benzo[d]imidazole-4-carboxylic acid, 1-Methyl-3-(trifluoromethyl)-1h-pyrazole-5-carboxylic acid, 2-Morpholin-4-yl-isonicotinic acid, 1,3-Oxazole-4-carboxylic acid, 4-Carboxybenzenesulfonamide, and 3,4-difluorobenzenesulfonyl chloride.

5 . (canceled)

6 . The engineered binder of claim 2 having a substrate binding pocket with a volume from about 200 Å 3 to about 2000 Å 3 .

7 . The engineered binder of claim 1 , wherein the engineered binder comprises an amino acid sequence having at least about 89% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 7—SEQ ID NO: 20.

8 . The engineered binder of claim 1 , wherein binding specificity between the engineered binder and the N-terminally modified target polypeptide is predominantly or substantially determined by interaction between the engineered binder and the M-P1 of the N-terminally modified target polypeptide.

9 . The engineered binder of claim 8 , wherein the engineered binder is capable of specifically binding to each N-terminally modified target polypeptide from a plurality of N-terminally modified target polypeptides, wherein the plurality of N-terminally modified target polypeptides comprises at least 10 N-terminally modified target polypeptides that are modified with the same N-terminal modifier agent, have the same modified NTAA residue, and have different P2 residues.

10 . The engineered binder of claim 1 , having an affinity towards an N-terminally modified target polypeptide comprising a specific P1 residue that is at least 2-fold higher as compared to affinity of the engineered binder towards an otherwise identical N-terminally modified target polypeptide but comprising a different P1 residue.

11 . The engineered binder of claim 1 , wherein the N-terminally modified target polypeptide is immobilized on a solid support.

12 . The engineered binder of claim 1 , further comprising a detectable label or a nucleic acid tag.

13 . A set of engineered binders, comprising at least two engineered binders, wherein:

each engineered binder from the set of engineered binders is configured to specifically bind to an N-terminally modified target polypeptide modified with an N-terminal modifier agent and having a formula: M-P1-P2-polypeptide, wherein M is an N-terminal modification, P1-P2-polypeptide is a target polypeptide before modification with the N-terminal modifier agent, M-P1 is a modified N-terminal amino acid (NTAA) residue of the target polypeptide, and P2 is a penultimate terminal amino acid residue of the target polypeptide;

(ii) each engineered binder from the set of engineered binders is configured to specifically bind to the N-terminally modified target polypeptide through interaction between the engineered binder and the modified NTAA residue of the N-terminally modified target polypeptide, wherein engineered binders from the set of engineered binders are configured to specifically bind to different modified NTAA residues of target polypeptides modified with the same or different N-terminal modifier agents; and

at least one engineered binder from the set of engineered binders comprises an amino acid sequence having at least about 80% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 7—SEQ ID NO: 20.

14 . The set of engineered binders of claim 13 , wherein at least one engineered binder from the set of engineered binders comprises an amino acid sequence having at least about 89% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 7—SEQ ID NO: 20.

15 . (canceled)

16 . The set of engineered binders of claim 13 , which further comprises least one engineered binder from the set of engineered binders comprising an amino acid sequence having at least about 80% sequence identity to the amino acid sequence set forth in SEQ ID NO: 63.

17 . The set of engineered binders of claim 13 , wherein each engineered binder from the set of engineered binders is configured to specifically bind to each N-terminally modified target polypeptide from a plurality of N-terminally modified target polypeptides, wherein the plurality of N-terminally modified target polypeptides comprises at least 10 N-terminally modified target polypeptides that are modified with the same N-terminal modifier agent, have the same modified NTAA residue, and have different P2 residues.

18 . (canceled)

19 . The set of engineered binders of claim 13 , wherein each engineered binder from the set of engineered binders comprises a detectable label or a nucleic acid tag.

20 . A method of treating a target polypeptide, the method comprises:

(i) contacting a target polypeptide with an N-terminal modifier agent to form an N-terminally modified polypeptide having a formula: M-P1-P2-polypeptide, wherein M is an N-terminal modification, P1-P2-polypeptide is a target polypeptide before modification with the N-terminal modifier agent, M-P1 is a modified N-terminal amino acid (NTAA) residue of the target polypeptide, and P2 is a penultimate terminal amino acid residue of the target polypeptide; and contacting an engineered binder with the N-terminally modified target polypeptide to allow the engineered binder to specifically bind to the N-terminally modified target polypeptide through interaction between the engineered binder and the modified NTAA residue of the N-terminally modified target polypeptide, wherein the engineered binder comprises an amino acid sequence having at least about 80% sequence identity to the amino acid sequence selected from the group consisting of SEQ ID NO: 7—SEQ ID NO: 20.

21 . (canceled)

22 . The method of claim 20 , wherein the N-terminal modifier agent is selected from the group consisting of compounds of the following formula:

(A)

wherein R is CH 3 , CF 3 , OC(CH 3 ) 3 , or OCH 2 C 6 H 5 ,

and X is H, CH 3 , CF 3 , CF 2 H, or OCH 3 ;

(B)

wherein X is H, CH 3 , CF 3 , CF 2 H, OCH 3 , or SO 2 NH 2 ;

(C)

wherein X is H, F, Cl, OCH 3 , OCF 3 , CN, or SO 2 NH 2 ,

and LG is succinimide, pentafluorophenyl, or tetrafluorophenyl; and

(D)

wherein X is H, F, Cl, NH 2 , OCH 3 , OCF 3 , CN, or SO 2 NH 2 , A=CONH or SO 2 , G=0 or 1 CH 2 ,

R is any amino acid or unnatural amino acid moiety, and

Z ring=0 (not there), 1, 2, or 3 CH 2 .

23 - 24 . (canceled)

25 . The method of claim 20 , further comprising immobilizing the target polypeptide on a solid support before step (i).

26 . The method of claim 22 , wherein the N-terminal modifier agent further comprises a peptide coupling reagent.

27 . (canceled)

28 . An isolated nucleic acid molecule comprising a polynucleotide having a sequence encoding the engineered binder of claim 1 .