Distinctive Distribution of Secretory Phospholipases A₂ in the Venoms of Afro-Asian Cobras (Subgenus: , , and ).

The protein abundances of phospholipases A₂ in cobra venom proteomes appear to vary among cobra species. To determine the unique distribution of snake venom phospholipases A₂ (svPLA₂) in the cobras, the svPLA₂ activities for 15 cobra species were examined with an acidimetric and a colorimetric assay, using egg yolk suspension and 4-nitro-3-octanoyloxy benzoic acid (NOBA) as the substrate. The colorimetric assay showed significant correlation between svPLA₂ enzymatic activities with the svPLA₂ protein abundances in venoms. High svPLA₂ activities were observed in the venoms of Asiatic spitting cobras (, ) and moderate activities in Asiatic non-spitters (, , ), African spitters (subgenus ), and forest cobra (subgenus ). African non-spitting cobras of subgenus (, , , ) showed exceptionally low svPLA₂ enzymatic activities. The negligible PLA₂ activity in cobra venoms implies that PLA₂ may not be ubiquitous in all snake venoms. The svPLA₂ in cobra envenoming varies depending on the cobra species. This may potentially influence the efficacy of cobra antivenom in specific use for venom neutralization.