Peptide biosensors for anthrax protease

A protease biosensor that detects lethal factor from Bacillus anthracis comprising

• a) a peptide comprising an amino acid sequence of the general formula I:
• X-Pro-Y-Z-W
• wherein X is between 5 and 13 amino acids, wherein at least one amino acid is selected from the group consisting of Arg, Lys, or His, and wherein none are Asp or Glu;
• Y is selected from the group consisting of hydrophobic amino acids or Gly;
• Z is selected from the group consisting of uncharged amino acids;
• and
• W is between 2 and 10 amino acids of any type;
• b) a fluorescent donor molecule attached to the peptide that is capable of participating in fluorescence resonance energy transfer;
• and
• c) an acceptor molecule attached to the peptide that has an absorption spectrum overlapping the emission spectrum of the donor molecule, wherein the fluorescence donor molecule and the acceptor molecule are attached to amino acid residues that are on opposite sides of the cleavage site.