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Paper Description


Lebetin peptides: potent platelet aggregating inhibitors


Authors: Naziha MARRAKCHI, Kamel MABROUK., Imed REGAYA, Sameh SARRAY, Mohamed Fathallah, Hervé ROCHAT and Mohamed EL Ayeb.
Abstract: Lebetins from Macrovipera lebetina snake venom constitute a new class of
inhibitors of platelet aggregation. There are two groups of peptides: lebetin 1
(L1; 11- to 13-mer) and lebetin 2 (L2; 37- to 38-mer). The short lebetins are
identical to the N-terminal segments of the longer ones. They inhibit platelet
aggregation induced by various agonists (e.g. thrombin, PAF-acether or collagen).
The shortest lebetin (11-mer) shows potent inhibition of rabbit (IC(50) = 7 nM)
and human (IC(50) = 5 nM) platelets. They prevent collagen-induced
thrombocytopenia in rats. N- and C-terminal-truncated synthetic L1gamma
(sL1gamma; 11-mer) is less active in inhibiting platelet aggregation than the
native peptide. Results from Ala scan studies of the sL1gamma peptide indicated
that replacement of the residues (P3, G7, P8, P9 or N10) resulted in a remarkable
drop in the activity, whereas replacement of residues K2, P4 or K6 by Ala
resulted in enhancement of the antiplatelet activity by at least 10-fold. To
examine the activity of multimeric L1gamma, several multimeric peptides were
synthesized using the multiple-antigen peptide system assembled on a branched
lysine core and their antiplatelet activity was evaluated in vitro. The largest
multimeric peptides showed a 1,000-fold increase in antiplatelet activity.
Published in: Haemostasis;31(3):207-210
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