A protease inhibitor of the Kunitz family from skin secretions of the tornato frog, Dyscophus guineti (Microhylidae)

J. Michael Conlon, Joseph B. Kim

Research output: Contribution to journalArticlepeer-review

53 Citations (Scopus)

Abstract

Norepinephrine-stimulated skin secretions of the tomato frog, Dyscophus guineti, contained a trypsin inhibitor whose primary structure was established as: SPAEVCF LPK10 ESGLCRARAL20 RYYYDRGDGK30 CEEFIYGGCG40 GNGNNY KSLL50 TCKISCE. This amino acid sequence identifies the peptide as a member of the Kunitz/bovine pancreatic trypsin inhibitor (BPTI) family and demonstrates that selective evolutionary pressure has acted to conserve those domains in the molecule (corresponding to positions 12-18 and 34-39 in BPTI) that interact with trypsin. Extracellular proteases produced by pathogenic microorganisms play important roles in facilitating invasion of the host and broad spectrum antimicrobial activity of BPTI has been described. Cationic, amphipathic α-helical antimicrobial peptides of the magainin type, important in the defense strategy of several species of frog, were not detected in the skin secretions. We speculate, therefore, that synthesis of a proteinase inhibitot in the skin of the tomato frog may be a component of an alternative strategy of this animal to defend itself against microorganisms.

Original languageEnglish
Pages (from-to)961-964
Number of pages4
JournalBiochemical and Biophysical Research Communications
Volume279
Issue number3
DOIs
Publication statusPublished (in print/issue) - 29 Dec 2000

Keywords

  • Amphibia
  • Antimicrobial peptide
  • Bovine pancreatic trypsin inhibitor
  • Kunitz
  • Protease inhibitor
  • Skin secretions

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