HCV protease substrates

1. A hepatitis C virus NS3 protease substrate comprising the following structure:

(B) n -X 1 -X 2 -X 3 -X 4 -X 5 -X 6 -X 7 -X 8 -X 9 -(Z) m

(SEQ ID NO:1)

wherein each B is an independently selected amino acid;

X 1 is either aspartic acid or glutamic acid;

X 2 is aspartic acid;

X 3 is methionine;

X 4 is glutamic acid;

X 5 is glutamic acid;

X 6 is 2-aminobutyric acid;

X 7 is alanine;

X 8 is serine;

X 9 is either lysine, histidine, cysteine or arginine;

each Z is an independently selected amino acid;

n is 0 to 10;

m is 0 to 10;

provided that X 6 is joined to X 7 by an ester linkage;

further provided that either: (a) at least one of a (B) n amino acid or X 1 is labeled with europium, and at least one of X 9 or an (Z) m amino acid is labeled with a quenching group; or (b) at least one of a (B) n amino acid or X 1 is labeled with a quenching group, and at least one of X 9 or an (Z) m amino acid is labeled with europium; and

further provided that the amino terminus amino acid is optionally modified with an amino terminus protecting group and the carboxyl terminus amino acid is optionally modified with a carboxyl terminus protecting group.

2. The substrate of claim 1 , wherein said polypeptide consists of said structure and said quenching group is QSY7.

3. The substrate of claim 2 , wherein n is 0 to 5, and m is 0 to 5.

4. The substrate of claim 3 , wherein n is 1.

5. The substrate of claim 4 , wherein said polypeptide consists of the following structure:

(SEQ ID NO:2)

wherein Eu is europium, Q is said quenching group, and Ac is acetyl.

6. A method of assaying hepatitis C virus (HCV) protease activity comprising the steps of:

(a) combining together HCV NS3, HCV NS4A, and the substrate of claim 1 , under conditions wherein said NS3 is active, and

(b) measuring europium signal production as an indication of HCV protease activity.