Reagents and procedures for high-specificity labeling

1. A molecule with two pendant phenylarsine moieties according to the general structural Formula (I) and tautomers, acids, and salts thereof:

wherein:

(i) each R 1 or R 2 , independently, is O − , S − , OR 3 or SR 3 with the provision that if either R 1 or R 2 is absent, the other remaining group is ═O or ═S; or R 1 and R 2 , together with the arsenic atom, form a ring according to one of the general structural Formulae (II), (III), (IV), or (V):

wherein R 3 is H, CH(OH)CH 2 OH or (CH 2 ) q —Y, wherein q is 1–4, and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN;

and Z represents a hydrocarbon chain comprising 2–4 singly or doubly bonded carbon atoms wherein each carbon atom may be further substituted with one or more groups selected from hydrogen, methyl, ethyl, 1-propyl, 2-propyl, methoxy, hydroxy, amino, carboxy, sulfo, oxo, thiol, halo (fluoro, chloro, bromo, or fluoro), (CH 2 ) n″ SO 3 —, and (CH 2 ) n″ SO 3 H, wherein n″ is 1 or 2;

(ii) R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring;

(iii) R 8 is a linear or branched optionally substituted spacer having a minimum length of approximately 1.5 and a maximum length of approximately 15 Ångstroms; and

(iv) X is a detectable group, wherein X is a fluorochrome.

2. The molecule according to claim 1 , wherein R 8 has a minimum length of about 3.5 Ångstroms and a maximum length of about 10 Ångstroms.

3. The molecule according to claim 1 , wherein R 8 has a minimum length of about 1 atom and a maximum length of about 9 atoms.

4. The molecule according to claim 1 , wherein X is a fluorescent moiety.

5. The molecule according to claim 1 , wherein X is derived from a cyanine dye.

6. The molecule according to claim 1 , wherein X is derived from a squaraine dye.

7. The molecule according to claim 1 , where X is selected from the group consisting of:

a.

(XII)

b.

(XIII)

c.

(XIV)

d.

(XV)

e.

(XVI)

wherein U and V are each independently C(R 14 ) 2 , NH, O, S, or (CH) 2 ; R 9 and R 10 are each independently H or sulfonate; R 14 is H, CH 3 , CH 2 CH 3 , or (CH 2 ) 2 CH 3 ; and n is 0 or an integer of from 1 to 6.

8. The molecule according to claim 1 , wherein n is 1, 2 or 3.

9. The molecule according to claim 1 , wherein X is selected from the group consisting of:

a.

(XVII)

b.

(XVIII)

c.

(XIX)

d.

(XX)

e.

(XXI)

f.

(XXII)

g.

(XXIII)

h.

(XXIV)

i.

(XXV)

wherein U and V are each independently C(R 14 ) 2 , NH, O, S, or (CH) 2 ; R 9 and R 10 are each independently H or sulfonate; R 13 is absent or is selected from the group consisting of H, an alkyl group, and an aryl group; R 14 is H, CH 3 , CH 2 CH 3 , or (CH 2 ) 2 CH 3 ; and n′ is 0 or an integer from 1 to 3.

10. The molecule according to claim 9 , wherein n′ is 0, 1, or 2.

11. The molecule according to claim 1 , wherein said molecule is capable of traversing a biological membrane.

12. A molecule with two pendant phenylarsine moieties according to the general structural Formula (VI):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , or N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH or (CH 2 ) q —Y, wherein q is 1–4 and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; and R 9 and R 10 are each independently selected from the group consisting of H and sulfonate.

13. A molecule with two pendant phenylarsine moieties according to the general structural Formula (VII):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH or (CH 2 ) q —Y, wherein q is 1–4, and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; and R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; and R 9 and R 10 are each independently selected from the group consisting of H and sulfonate.

14. A molecule with two pendant phenylarsine moieties according to the general structural Formula (VIII):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH, or (CH 2 ) q —Y, wherein q is 1–4 and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; and R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; and R 9 and R 10 are each independently selected from the group consisting of H and sulfonate.

15. A molecule with two pendant phenylarsine moieties according to the general structural Formula (IX):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH or (CH 2 ) q —Y, wherein q is 1–4 and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; R 9 and R 10 are each independently selected from the group consisting of H and sulfonate; and R 11 and R 12 are each independently selected from the group consisting of H, (CH 2 ) n″ SO 3 —, and (CH 2 ) n″ SO 3 H, wherein n″ is 1 or 2.

16. A molecule with two pendant phenylarsine moieties according to the general structural Formula (X):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH, or (CH 2 ) q —Y, wherein q is 1–4 and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; R 9 and R 10 are each independently selected from the group consisting of H and sulfonate; and R 11 and R 12 are each independently selected from the group consisting of H, (CH 2 ) n″ SO 3 —, and (CH 2 ) n″ SO 3 H, wherein n″ is 1 or 2.

17. A molecule with two pendant phenylarsine moieties according to the general structural Formula (XI):

wherein R 4 , R 5 , R 6 and R 7 are each independently H, F, OR 3 , R 3 , OAc, NH 2 , N(C 1 –C 4 alkyl) 2 ; or R 4 with R 5 , or R 6 together with R 7 , or both, form a ring; wherein R 3 is H, CH(OH)CH 2 OH or (CH 2 ) q —Y, wherein q is 1–4 and Y is H, OH, NH 2 , SH, COOH, OAc, CONH 2 or CN; R 8 is a linear or branched optionally substituted spacer having a length of from approximately 1.5 to approximately 15 Ångstroms; R 9 and R 10 are each independently selected from the group consisting of H and sulfonate; and R 11 and R 12 are each independently selected from the group consisting of H, (CH 2 ) n″ SO 3 —, and (CH 2 ) n″ SO 3 H, wherein n″ is 1 or 2.

18. A kit comprising:

(a) a molecule according to Formula (I) of claim 1 ; and

(b) a molecule containing a target sequence, said target sequence comprising an amino acid sequence of the form: C(X) i C(X) j C(X) k C, wherein C is cysteine, X is any amino acid, and i, j, and k are each independently 0 or an integer of from 1 to 6.

19. A kit comprising:

(a) a molecule according to Formula (I) of claim 1 ; and

(b) a reagent that promotes the formation of a complex between said molecule according to Formula (I) and a peptide comprising a target sequence, said target sequence comprising an amino acid sequence of the form C(X) i C(X) j C(X) k C, wherein C is cysteine, X is any amino acid, and i, j, and k are each independently 0 or an integer of from 1 to 6.