Isolation and biological activity of a novel kinin ([Thr6] bradykinin) from the turtle, Pseudemys scripta

J. Michael Conlon, James W. Hicks, D. David Smith

Research output: Contribution to journalArticlepeer-review

33 Citations (Scopus)


Incubation of plasma from the red-eared turtle with glass beads in the presence of the kininase inhibitor 1,10-phenanthroline resulted in activation of the kallikrein-kinin system and generation of bradykinin-like immunoreactivity. The immunoreactive material comprised a single molecular form that was purified to homogeneity by reverse phase HPLC. The primary structure of the peptide was determined by automated Edman degradation and fast atom bombardment mass spectrometry. The amino acid sequence of the turtle kinin Arg-Pro-Pro-Gly-Phe-Thr-Pro-Phe-Arg contains the substitution Thr for Ser at position 6 compared with mammalian bradykinin. [Thr6] bradykinin was synthesized using solid phase methodology, and bolus injections of the peptide into the left atrium of the anaesthetized turtle produced rapid vasodilation. A dose-dependent increase in blood flow in the left aortic arch was accompanied by a decrease in peripheral vascular resistance, so that systemic blood pressure did not change. The data suggest that the kallikrein-kinin system may play an important physiological role in the regulation of cardiovascular function in reptiles.

Original languageEnglish
Pages (from-to)985-991
Number of pages7
Issue number2
Publication statusPublished - Feb 1990
Externally publishedYes

ASJC Scopus subject areas

  • Endocrinology


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