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Bradykinin‐related peptides from Phyllomedusa hypochondrialis azurea : mass spectrometric structural characterisation and cloning of precursor cDNAs
Author(s) -
Thompson Alan Hunter,
Bjourson Anthony John,
Shaw Chris,
McClean Stephen
Publication year - 2006
Publication title -
rapid communications in mass spectrometry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.528
H-Index - 136
eISSN - 1097-0231
pISSN - 0951-4198
DOI - 10.1002/rcm.2791
Subject(s) - chemistry , peptide , mass spectrometry , tandem mass spectrometry , complementary dna , biochemistry , gene isoform , chromatography , microbiology and biotechnology , gene , biology
Amphibian skin secretions contain a plethora of bioactive compounds, many of which are understood to act to deter ingestion by predators. Bradykinins in particular are constitutively expressed in many amphibian skin secretions, mediating a variety of effects including hyperalgesia and contraction of gastric smooth muscle. Using a variety of proteomic techniques (high‐performance liquid chromatography (HPLC) separation, matrix‐assisted laser desorption/ionisation time‐of‐flight mass spectrometry (MALDI‐TOFMS), and quadrupole time‐of‐flight tandem mass spectrometry (Q‐TOF‐MS/MS)) the current study identified 13 bradykinin‐like peptides in the skin secretions of Phyllomedusa hypochondrialis azurea , including several new C‐terminally extended isoforms (VPPGFTPFRLT, V Hyp PGFTPFRQT) and a novel phyllokinin‐like peptide (RPPGFTPFRVY). Identification of the cDNA sequences encoding these peptides led to the deduction that the peptides were derived from differential post‐translational processing and modification of five different precursors. Such an event emphasises the metabolic efficiency of peptide production in amphibian venom, with multiple products perhaps selective to different receptors in a variety of predators generated from a single precursor. An unusual modification was also recognised in the present study, with several bradykinin‐like peptides featuring hydroxyprolination of the first proline residue rather than the commonly targeted second. This alteration may be mediated by the structural organisation of N‐terminal amino acids prior to precursor processing. Copyright © 2006 John Wiley & Sons, Ltd.