Fluorescence assay for kinase activity

1. A peptide comprising:

(a) a metal binding amino acid of the formula (I):

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or alkyl;

n is 1, 2 or 3; and

(b) a β-turn sequence.

2. The peptide of claim 1 , further comprising a kinase recognition sequence.

3. The peptide of claim 1 , wherein the metal binding amino acid is of the formula (II):

where X is —OR″ or —NR″R′″;

R″ is C 1-6 alkyl; and R′″ is hydrogen or C 1-6 alkyl.

4. The peptide of claim 1 , wherein the metal binding amino acid is of the formula (III):

5. The peptide of claim 1 , which comprises the sequence (SID No.8):

H 2 N—X 1 —X 2 —X 3 —COOH

where X 1 is an amino acid of the formula (I)

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or alkyl;

n is 1, 2 or 3; and

X 2 and X 3 are each, independently, amino acid residues which together form a β-turn sequence.

6. The peptide of claim 5 , which comprises the sequence -Sox-Pro-Gly-.

7. The peptide of claim 1 , which comprises the sequence (SID No.9):

H 2 N—X 1 —X 2 —X 3 —X 4 —X 5 —COOH

where X 1 is an amino acid of the formula (I)

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or alkyl;

n is 1, 2 or 3;

X 2 and X 3 are each, independently, amino acid residues which together form a β-turn sequence;

X 4 is a bond or an amino acid residue; and

X 5 is peptidyl kinase recognition motif, where the hydroxyl amino acid of the recognition motif is connected to X 4 .

8. The peptide of claim 1 , which comprises the sequence (SID No.10):

H 2 N—X 3 —X 2 —X 1 —COOH

where X 1 is an amino acid of the formula (I)

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or alkyl;

n is 1, 2 or 3; and

x 2 and X 3 are each, independently, amino acids which together form a β-turn sequence.

9. The peptide of claim 8 , which comprises the sequence -Leu-Pro-Sox-.

10. The peptide of claim 1 , which comprises the sequence (SID No.11):

H 2 N—X 5 —X 4 —X 3 —X 2 —X 1 —COOH

where X 1 is an amino acid of the formula (I)

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or alkyl;

n is 1, 2 or 3;

X 2 and X 3 are each, independently, amino acids which together form a β-turn sequence;

X 4 is a bond or an amino acid residue; and

X 5 is peptidyl kinase recognition motif, where the hydroxyl amino acid of the recognition motif is connected to X 4 .

11. A capping group of the formula (IV):

where each R is independently hydrogen or —SO 2 X, wherein at least one R group is —SO 2 X and the remainder are hydrogen, where X is —OR″ or —NR″R′″;

R′ is hydroxy, amino, or thiol;

R″ is C 1-6 alkyl;

R′″ is hydrogen or C 1-6 alkyl; and

n=0, 1, 2, or 3.

12. A peptide where the N-terminus is protected with the capping group of claim 11 .