Analysis and Identification of Putative Novel Peptides Purified from Iranian Endemic Echis Carinatus Sochureki Snake Venom by MALDI-TOF Mass Spectrometry.

Abstract

The Iranian Echis Carinatus (IEC) venom is an exclusive natural source of bio-substances for a wide range of purposes in the blood coagulation cascade. The present study for the first time was aimed to assess novel pro-coagulant, anti-coagulant and anti-platelet proteins, named EC_{1.5 (a)}, EC_{5.1 (b)} and EC_{4 (a)} from Iranian Echis Carinatus (IEC) venom. These peptides were purified by multi-step chromatography methods. Hematological properties were measured using activated clotting tests, platelet aggregation studies, and hemorrhage assessment. Subsequently, these proteins were identified through both their intact molecular mass and peptide mass fingerprint (PMF) using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry (MALDI-TOF MS). Multiple sequence alignments were performed by ClustalW, Bioedit software. Molegro Data Modeller (MDM) 3.0 software was used to predict the putative tertiary structure of proteins.EC_{1.5 (a)}, a single-band protein with a molecular mass of 66 and 55 kDa, was observed by sodium dodecyl sulfate-polyacrylamide gel electrophoresis as a reduced and non-reduced state, respectively. Based on the Mascot results, we considered that EC_{1.5 (a)} is a metalloproteinase of group ΙΙ which exhibited potent pro-coagulant activity. It is predicted that the EC_{1.5 (a)} with hemorrhagic activity, potentially is a metalloproteinase/disintegrin region that constitutes the disintegrin-like domains. Our findings demonstrate that the disintegrin domain of EC_{1.5 (a)} lacks platelet aggregation inhibitory activity. On the contrary, this factor shows the property of a platelet aggregation inducer. Also, the EC_{5.1 (b)} was observed as a single-band protein with a molecular mass of 7.5 kDa. EC_{5.1 (b)} showed both anti-coagulant and anti-platelet properties. Additionally, the structure of the EC_{5.1 (b)} fraction is expected to be similar to that of phospholipase A₂, while EC_{4 (a)} structure is potentially very similar to that of Echistatin with 5 kDa molecular mass. We introduce the predicted structure of P-II snake venom metalloproteinase/ disintegrin domains, phospholipase A₂ and Echistatin-like fractions. Further research is therefore needed to determine the complete structure of these novel fractions and elucidate their mechanism of action and future therapeutic applications of cardiovascular and homeostasis disorders.