Background: Cerastes cerastes venom contains several bioactive proteins with inhibitory
potential of platelet aggregation and blood coagulation.
Objective: The current study deals with purification, characterization and determination of structural
properties of Cc-PDE, the first phosphodiesterase from Cerastes cerastes venom.
Material and Methods: The purification process consists of three successive chromatographies including
G75-Sephadex size exclusion, DEAE exchange chromatography and affinity using Sildenafil
as a main PDEs’ specific inhibitor. The amino acid sequence of purified Cc-PDE was determined
by liquid chromatography coupled off line to MALDI-TOF/TOF. Modeling and structural
features were obtained using several bioinformatics tools. In vivo and in vitro antiplatelet aggregation
and anticoagulant assays were performed.
Results: Cc-PDE (73 506.42 Da) is a 654-residue single polypeptide with 1-22 signal peptide and
it is characterized by the presence of predominant basic amino acids suitable to alkaline pI (8.17).
Cc-PDE structure is composed of β-strands (17%) and α-helices (24%) and it shares a high identity
with homologous snake venom PDEs. Cc-PDE hydrolyzes both Bis-p-nitrophenyl phosphate (Km
= 2.60 ± 0.95 mM, Vmax = 0.017 ± 0.002569 μmol.min-1) and p-nitrophenyl phosphate (Km =
7.13 mM ± 0.04490 mM, Vmax = 0.053 ±0.012 μmol.min-1). Cc-PDE prevents ADP- and ATP-induced
platelet aggregation by hydrolyzing ADP and ATP, reducing surface P-selectin expression
and attenuating platelet function. In addition, Cc-PDE inhibits coagulation factors involved in the
intrinsic pathway demonstrated by a significant prolongation of activated partial thromboplastin
time and in vivo long-lasting anticoagulation.
Conclusion: The obtained results revealed that Cc-PDE may have a therapeutic potential and could
be a remedy for thromboembolic diseases as an alternative of anticoagulant and antiplatelet aggregation