Antibiotic cryptdin peptides and methods of their use

A substantially purified mouse cryptdin peptide of enteric origin having an amino acid sequence as follows:

• X.sub.1 -L-X.sub.2 -C-Y-C-R-X.sub.3 -C-K-X.sub.4 -E-X.sub.5 -G-T-C-X.sub.6 -C-C-X.sub.7
• wherein
• X.sub.1 is 1, 3 or 4 amino acids;
• X.sub.2 is 1 amino acid;
• X.sub.3 is 3 amino acids;
• X.sub.4 is 2 amino acids;
• X.sub.5 is 3 amino acids;
• X.sub.6 is 6 to 9 amino acids;
• and
• X.sub.7 is 0 to 3 amino acids.

A substantially purified cryptdin peptide of enteric origin having an amino acid sequence selected from the group consisting of:

• GLLCYCRKGHCKRGERVRGTCGIRFLYCCPRR (SEQ ID NO:
• 12);
• LSKKLICYCRIRGCKRRERVFGTCRNLFLTFVFCCS (SEQ ID NO:
• 13);
• LRDLVCYCRARGCKGRERMNGTCRKGHLLYMLCCR (SEQ ID NO:
• 14);
• LKQCHCRKFCRPYEKAEGSCRPGLFIKRKICCIQQWTPGRT (SEQ ID NO:
• 15);
• IGRPVRRCRCRANCGPKEYATAFCAQGPFKQFKFCCT (SEQ ID NO:
• 16);
• IRWPWKRCHCRSFCRPYENATSFCAQGLFKQHKFCCLDTWPPRMK (SEQ ID NO:
• 10);
• TSGSQARATCYCRTGRCATRESLSGVCEISGRLYRLCCR (SEQ ID
• NO:
• 18);
• and
• AFTCHCRRSCYSTEYSYGTCTVMGINHRFCCL (SEQ ID NO:
• 19).

A substantially purified cryptdin peptide having the following characteristics:

• a) expressed endogenously in epithelial cells of the small intestine;
• b) having a cationic charge;
• c) consisting of 30 to 45 amino acids in length;
• d) consisting of three to nine amino acids N-terminal to the first cysteine residue;
• and
• e) exhibiting antimicrobial activity against intestinal pathogens and opportunistic pathogens.