摘要
The protein abundances of phospholipases A 2 in cobra venom proteomes appear to vary among cobra species. To determine the unique distribution of snake venom phospholipases A 2 (svPLA 2 ) in the cobras, the svPLA 2 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 svPLA 2 enzymatic activities with the svPLA 2 protein abundances in venoms. High svPLA 2 activities were observed in the venoms of Asiatic spitting cobras (Naja sputatrix, Naja sumatrana) and moderate activities in Asiatic non-spitters (Naja naja, Naja atra, Naja kaouthia), African spitters (subgenus Afronaja), and forest cobra (subgenus Boulengerina). African non-spitting cobras of subgenus Uraeus (Naja haje, Naja annulifera, Naja nivea, Naja senegalensis) showed exceptionally low svPLA 2 enzymatic activities. The negligible PLA 2 activity in Uraeus cobra venoms implies that PLA 2 may not be ubiquitous in all snake venoms. The svPLA 2 in cobra envenoming varies depending on the cobra species. This may potentially influence the efficacy of cobra antivenom in specific use for venom neutralization.