Abundance of Proteases in Nigerian Echis ocellatus Venom Revealed through Qualitative Proteomic Analysis

Abstract

Snake venom proteins are generally categorized into enzymatic and non-enzymatic classes, both of which play a crucial roles in the pathophysiology of envenoming. Echis ocellatus, a viper widely distributed across Nigeria, is responsible for a high proportion of snakebite-related morbidity and mortality in the region. Understanding the venom composition and its molecular complexity is essential for advancing venomics and improving antivenom design.In this study, comprehensive proteomic profiling was performed to characterize the enzymatic and non-enzymatic constituents of E. ocellatus venom. Liquid chromatography–mass spectrometry (LC-MS) analysis was conducted using the Advion TriVersa NanoMate nano-electrospray ionization (ESI) platform with chip-based LC-ESI-MS/MS technology. Proteins and peptides were identified and curated using coverage thresholds of ≥5%, ≥10%, and ≥20%. The enzymatic repertoire included numerous proteases, phosphodiesterases, phospholipase A₂ (PLA₂), arginine ester hydrolase, alkaline phosphomonoesterase, and 5′-nucleotidase. Notably, both phospholipases A₂ and B were detected, along with diverse snake venom metalloproteinases (SVMPs), which are key drivers of hemorrhage and tissue damage. Additional protein families identified included L-amino acid oxidases, cysteine-rich secretory proteins, venom nerve growth factors, as well as serine protease inhibitors, aminopeptidases, and acetylcholinesterases. In total, 163 proteins were identified, reflecting the high toxic potency and complexity of the venom. These findings provide valuable insight into E. ocellatus venom composition and support future development of improved antivenoms and venom-derived therapeutic candidates through quantitative proteomics.