Isolation and properties of a new kallikrein inhibitor from Tityus serrulatus venom

The kallikrein inhibitor-peptide content of Tityus serrulatus scorpion crude venom was purified by Sephadex G-50 and Sephadex G-25 fine gel filtration chromatographies, followed by two steps of reverse-phase column on HPLC. The isolated inhibitor peptide was homogeneous in its N-terminal and partial amino acid sequence, showing a molecular weight of 4.489 Da by mass spectrometry and amino acid analysis. The peptide was tested with rat plasma and urine kallikrein, which resulting in an inhibition with similar affinity to both enzymes, showing an IC(50) of 14.3 ìM after 13 and 8 min, respectively, using kininogen as substrate on the isolated guinea-pig ileum bioassay. The porcine pancreatic kallikrein showed after 10 min an IC(50) value of 12.6 ìM with H-D-Val-Leu-Arg-pNA HCl as substrate. In addition, the isolated peptide significantly inhibited porcine pancreatic kallikrein with values in the range of apparent or absolute calculated peptide K(i) = 2.5 ìM. The inhibitor was heat resistant and stable at pH values less than 5

Measurement of bradykinin, protein Na+, CL-, K+, and Zn+ concentrations in rat urine after intraperitoneal injection of Tityus serrulatus venom

Experiments were carried out in vivo by injecting Tityus serrulatus crude venom in rats followed by biological assays on the isolated guinea-pig ileum, to show the effects of scorpion venom on kallikrein-kinin system. Our results showed effects such as significant decrease of total kinin rate and a decrease of total kinin rate and a decrease of Zn++, Na+, Cl- and K+ ions in rat urine 24 and 48 hours after the injection of Tityus serrulatus crude venom.