Antimicrobial peptides and protease inhibitors in the skin secretions of the crawfish frog, Rana areolata

Mohamed F. Ali, Karen R. Lips, Floyd C. Knoop, Bernd Fritzsch, Caroline Miller, J. Michael Conlon

Research output: Contribution to journalArticlepeer-review

103 Citations (Scopus)


The dorsal skin of the crawfish frog, Rana areolata, is associated with numerous prominent granular glands. Proteomic analysis of electrically stimulated skin secretions from these glands enabled the identification and characterization of eight peptides with antimicrobial and hemolytic activity belonging to the previously identified brevinin-1, temporin-1, palustrin-2, palustrin-3, esculentin-1 (two peptides), and ranatuerin-2 (two peptides) families. The primary structures of the peptides were consistent with a close phylogenetic relationship between R. areolata and the pickerel frog, Rana palustris. Three structurally related cationic, cysteine-containing peptides were identified that show sequence similarity to peptide Leucine-Arginine, a peptide with immunomodulatory and histamine-releasing properties from the skin of the northern leopard frog, Rana pipiens. The skin secretions contained a 61-amino-acid-residue peptide that inhibited porcine trypsin and possessed a 10-cysteine-residue motif that is characteristic of a protease inhibitor previously isolated from the parasitic nematode, Ascaris suum. A 48-amino-acid-residue protein containing eight cysteine residues in the whey acidic protein (WAP) motif, characteristic of elafin (skin-derived antileukoproteinase) and secretory leukocyte protease inhibitor, was also isolated. The data suggest that protease inhibitors in skin secretions may play a role complementary to cationic, amphipathic α-helical peptides in protecting anurans from invasions by microorganisms.

Original languageEnglish
Pages (from-to)55-63
Number of pages9
JournalBiochimica et Biophysica Acta - Proteins and Proteomics
Issue number1
Publication statusPublished (in print/issue) - 19 Nov 2002


  • Amphibian skin
  • Antimicrobial peptide
  • Elafin
  • Rana
  • Trypsin inhibitor


Dive into the research topics of 'Antimicrobial peptides and protease inhibitors in the skin secretions of the crawfish frog, Rana areolata'. Together they form a unique fingerprint.

Cite this