Biochemical and Monolayer characterization of Tunisian snake venom phospholipases

Douja Bairam (1, 2) , Imen Aissa (3, 4) , Hanen Louati (3, 4) , Houcemeddine Othman (1, 2) , Zaineb Abdelkafi-Koubaa (1, 2) , Najeh Krayem (3, 4) , Mohamed El Ayeb (1, 2) , Najet Srairi-Abid (1, 2) , Naziha Marrakchi (1, 2) , Youssef Gargouri (3, 4)

1 LR11IPT08 - Laboratoire des Venins et Biomolécules Thérapeutiques - Laboratory of Venoms and Therapeutic Biomolecules
2 UTM - Université de Tunis El Manar
3 Université de Sfax - University of Sfax
4 ENIS - École Nationale d'Ingénieurs de Sfax | National School of Engineers of Sfax

The present study investigated the kinetic and interfacial properties of two secreted phospholipases isolated from Tunisian vipers'venoms: Cerastes cerastes (CC-PLA2) and Macrovipera lebetina transmediterranea (MVL-PLA2). Results show that these enzymes have great different abilities to bind and hydrolyse phospholipids. Using egg-yolk emulsions as substrate at pH 8, we found that MVL-PLA2 has a specific activity of 1473 U/mg at 37 degrees C in presence of 1 mM CaCl2. Furthermore the interfacial kinetic and binding data indicate that MVL-PLA2 has a preference to the zwitterionic phosphatidylcholine monolayers (PC). Conversely, CC-PLA2 was found to be able to hydrolyse preferentially negatively charged head group phospholipids (PG and PS) and exhibits a specific activity 9 times more important (13 333 U/mg at 60 degrees C in presence of 3 mM CaCl2). Molecular models of both CC-PLA2 and MVL-PLA2 3D structures have been built and their electrostatic potentials surfaces have been calculated. A marked anisotropy of the overall electrostatic charge distribution leads to a significantly difference in the dipole moment intensity between the two enzymes explaining the great differences in catalytic and binding properties, which seems to be governed by the electrostatic and hydrophobic forces operative at the surface of the two phospholipases

Mots clés: Phospholipase A2; Biochemical characterization; Biochemical characterization; Phospholipase A2; Phospholipid monolayers

Domaines: Sciences du Vivant [q-bio]

Douja Bairam, Imen Aissa, Hanen Louati, Houcemeddine Othman, Zaineb Abdelkafi-Koubaa, et al.. Biochemical and Monolayer characterization of Tunisian snake venom phospholipases. International Journal of Biological Macromolecules, 2016, 89, pp.640-646. ⟨10.1016/j.ijbiomac.2016.05.020⟩. ⟨pasteur-01405543⟩