Target sequences for synthetic molecules

1. A method of labeling a carrier molecule, comprising:

a) providing a bonding partner comprising the carrier molecule and a target sequence, and

b) contacting the bonding partner with a biarsenical molecule under conditions wherein the biarsenical molecule reacts with the target sequence, wherein the target sequence comprises Cys-Cys-X 1 -X 1 -X 2 -X 1 -X 3 -X 1 -X 1 -Cys-X 1 -Cys-X 2 (SEQ. ID NO: 3), wherein:

X 1 is an amino acid having a non-polar side chain,

X 2 is an amino acid having a basic side chain, and

X 3 is an amino acid having a non-ionic polar side chain, and

wherein the biarsenical molecule has the formula:

and tautomers, anhydrides, and salts thereof;

wherein:

each X 1 or X 2 is independently Cl, Br, I, OR a , or SR a , or

X 1 and X 2 together with the arsenic atom form a ring having the formula:

R a is H, C 1 -C 4 alkyl, CH 2 CH 2 OH, CH 2 COOH, or CN;

Z is 1,2-ethanediyl, 1,2-propanediyl, 2,3-butanediyl,

1,3-propanediyl, 1,2 benzenediyl, 4-methyl-1,2-benzenediyl,

1,2-cyclopentanediyl, 1,2-cyclohexanediyl, 3-hydroxy-1,2-propanediyl, 3-sulfo-1,2-propanediyl, or 1,2-bis(carboxy)-1,2-ethanediyl;

Y 1 and Y 2 are each independently H or CH 3 , or

Y 1 and Y 2 together form a ring such that the biarsenical molecule has the formula

wherein:

M is O, S, CH 2 , C(CH 3 ) 2 , or NH;

R 1 and R 2 are each independently OR a , OAc, NR a R b , or H;

R 3 and R 4 are each independently H, F, Cl, Br, I, OR a , or R a ; or

R 1 together with R 3 , or R 2 together with R 4 , or both, form a ring in which

(i) one of R 1 or R 3 is C 2 -C 3 alkyl and the other is NR a and

(ii) one of R 2 and R 4 is C 2 -C 3 alkyl and the other is NR a ;

R b is H, C 1 -C 4 alkyl, CH 2 CH 2 OH, CH 2 COOH, or CN;

Q is CR a R b , CR a OR b , C═O, or a spirolactone having the formula:

wherein the Spiro linkage is formed at C 1 .

2. The method of claim 1 , wherein the biarsenical molecule generates a detectable signal.

3. The method of claim 2 , further comprising monitoring the detectable signal.

4. The method of claim 2 , wherein the signal is a fluorescent signal.

5. The method of claim 1 , wherein the biarsenical molecule is coupled to a solid phase.

6. The method of claim 1 , wherein the target sequence is coupled to a solid phase.

7. The method of claim 1 , wherein the carrier molecule is a polypeptide.

8. The method of claim 7 , wherein the polypeptide is an antibody or an enzyme.

9. The method of claim 1 , wherein X 1 is glycine, alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, or tryptophan.

10. The method of claim 1 , wherein X 2 is lysine, arginine, or histidine.

11. The method of claim 1 , wherein X 3 is asparagine, glutamine, serine, or threonine.

12. The method of claim 1 , wherein the target sequence is Cys-Cys-gly-gly-lys-gly-asn-gly-gly-Cys-gly-Cys-his (SEQ. ID NO: 50).

13. A method of purifying a bonding partner, comprising:

a) providing a bonding partner comprising a target sequence wherein the target sequence comprises Cys-Cys-X 1 -X 1 -X 1 -X 1 -X 3 -X 1 -X 1 -Cys-X 1 -Cys-X 2 (SEQ. ID NO: 3), wherein:

X 1 is an amino acid having a non-polar side chain,

X 2 is an amino acid having a basic side chain, and

X 3 is an amino acid having a non-ionic polar side chain, and

wherein the target sequence reacts with a biarsenical molecule having the structure:

and tautomers, anhydrides, and salts thereof;

wherein:

each X 1 or X 2 is independently Cl, Br, I, OR a , or SR a , or

X 1 and X 2 together with the arsenic atom form a ring having the formula:

R a is H, C 1 -C 4 alkyl, CH 2 CH 2 OH, CH 2 COOH, or CN;

Z is 1,2-ethanediyl, 1,2-propanediyl, 2,3-butanediyl, 1,3-propanediyl,

1,2 benzenediyl, 4-methyl-1,2-benzenediyl, 1,2-cyclopentanediyl,

1,2-cyclohexanediyl, 3-hydroxy-1,2-propanediyl, 3-sulfo-1,2-propanediyl, or

1,2-bis(carboxy)-1,2-ethanediyl;

Y 1 and Y 2 are each independently H or CH 3 , or

Y 1 and Y 2 together form a ring such that the biarsenical molecule has the formula

wherein:

M is O, S, CH 2 , C(CH 3 ) 2 , or NH;

R 1 and R 2 are each independently OR a , OAc, NR a R b , or H;

R 3 and R 4 are each independently H, F, Cl, Br, I, OR a , or R a ; or

R 1 together with R 3 , or R 2 together with R 4 , or both, form a ring in which

(i) one of R 1 or R 3 is C 2 -C 3 alkyl and the other is NR a and

(ii) one of R 2 and R 4 is C 2 -C 3 alkyl and the other is NR a ;

R b is H, C 1 -C 4 alkyl, CH 2 CH 2 OH, CH 2 COOH, or CN;

Q is CR a R b , CR a OR b , C═O, or a spirolactone having the formula:

wherein the Spiro linkage is formed at C 1 ;

b) contacting the bonding partner with the biarsenical molecule, wherein the biarsenical molecule is coupled to a solid phase, and

c) eluting the bonding partner from the biarsenical molecule by contacting the biarsenical molecule with a dithiol.

14. The method of claim 13 , wherein the carrier molecule is a protein.

15. The method of claim 14 , wherein the protein is an antibody or an enzyme.

16. The method of claim 13 , wherein the biarsenical compound is membrane permeable.

17. The method of claim 13 , wherein the dithiol is selected from the group consisting of 1,2-benzendithiol, 1,2-cyclohexanedithiol and 1,2-ethanedithiol.

18. The method of claim 13 , wherein X 1 of SEQ ID NO: 3 is glycine, alanine, valine, leucine, isoleucine, methionine, proline, phenylalanine, or tryptophan.

19. The method of claim 13 , wherein X 2 of SEQ ID NO:3 is lysine, arginine, or histidine.

20. The method of claim 13 , wherein X 3 of SEQ ID NO:3 is asparagine, glutamine, serine, or threonine.

21. The method of claim 13 , wherein the target sequence is Cys-Cys-Gly-Gly-Lys-Gly-Asn-Gly-Gly-Cys-Gly-Cys-His (SEQ. ID. NO: 50).

22. The method of claim 13 , wherein the biarsenical molecule has the following structure:

23. The method of claim 1 , wherein the biarsenical molecule has the following structure: