A thermoactive l-amino acid oxidase from Cerastes cerastes snake venom: Purification, biochemical and molecular characterization.

Zaineb Abdelkafi-Koubaa (1) , Jed Jebali (1) , Houcemeddine Othman (1) , Maram Morjen (1) , Imen Aissa (2) , Raoudha Zouari-Kesentini (1) , Amine Bazaa (1) , Amen Allah Ellefi (1) , Hafedh Majdoub (3) , Najet Srairi-Abid (1) , Youssef Gargouri (2) , Mohamed El Ayeb (1) , Naziha Marrakchi (4, 1)

1 LR11IPT08 - Laboratoire des Venins et Biomolécules Thérapeutiques - Laboratory of Venoms and Therapeutic Biomolecules
2 Laboratoire de Biochimie et de Génie Enzymatique des Lipases
3 USCR Séquenceur de Protéines
4 Faculté de Médecine de Tunis

A new l-amino acid oxidase (LAAO) from Cerastes cerastes snake venom, named CC-LAAO, was purified to homogeneity using a combination of size-exclusion, ion-exchange and affinity chromatography. CC-LAAO is a homodimeric glycosylated flavoprotein with a molecular mass around 58 kDa under reducing conditions and about 115 kDa in its native form when analyzed by SDS-PAGE and gel filtration chromatography, respectively. This enzyme displayed a Michaelis-Menten behavior with an optimal pH at 7.8. However, unlike known SV-LAAOs which display their maximum activity at 37 °C, CC-LAAO has an optimal temperature at 50 °C. Kinetic studies showed that the enzyme displayed high specificity towards hydrophobic l-amino acids. The best substrates were L-Phe, L-Met and L-Leu. CC-LAAO activity was inhibited by the substrate analog N-acetyl tryptophan. The N-terminal amino acid sequence of this protein was determined by automated Edman degradation. The CC-LAAO cDNA was cloned from the venom gland total RNA preparation. The cDNA sequence contained an open-reading frame (ORF) of 1551-bp, which encoded a protein of 516 amino acids comprising a signal peptide of 18 amino acids and 498-residues mature protein. CC-LAAO sequence and its tertiary model shared high similarity with other snake venom LAAOs.

Keywords: Snake venom; L -amino acid oxidase; Glycosylation; cDNA sequence; Tertiary model

Domains: Life Sciences [q-bio]; Life Sciences [q-bio]; Toxicology

Zaineb Abdelkafi-Koubaa, Jed Jebali, Houcemeddine Othman, Maram Morjen, Imen Aissa, et al.. A thermoactive l-amino acid oxidase from Cerastes cerastes snake venom: Purification, biochemical and molecular characterization.. Toxicon, 2014, 89, pp.32-44. ⟨10.1016/j.toxicon.2014.06.020⟩. ⟨pasteur-01059902⟩