Biochemistry Department, Science College, King Saud University, P.O. Box 22452, Riyadh 11495, Saudi Arabia.
Laboratoire de Biochimie et de Génie Enzymatique des Lipases, ENIS, Université de Sfax, Route de Soukra 3038, Sfax BP 1173, Tunisia.
Molecules. 2023 Sep 8;28(18):6517. doi: 10.3390/molecules28186517.
Secreted phospholipases A are snake-venom proteins with many biological activities, notably anti-tumor activity. Phospholipases from the same snake type but different geographical locations have shown similar biochemical and biological activities with minor differences in protein sequences. Thus, the discovery of a new phospholipase A with unique characteristics identified in a previously studied venom could suggest the origins of these differences. Here, a new Group II secreted phospholipase A (Cc-PLA-II) from the snake venom of Saudi was isolated and characterized. The purified enzyme had a molecular weight of 13.945 kDa and showed high specific activity on emulsified phosphatidylcholine of 1560 U/mg at pH 9.5 and 50 °C with strict calcium dependence. Interestingly, stability in extreme pH and high temperatures was observed after enzyme incubation at several pH levels and temperatures. Moreover, a significant dose-dependent cytotoxic anti-tumor effect against six human cancer cell lines was observed with concentrations of Cc-PLA ranging from 2.5 to 8 µM. No cytotoxic effect on normal human umbilical-vein endothelial cells was noted. These results suggest that Cc-PLA-II potentially has angiogenic activity of besides cytotoxicity as part of its anti-tumor mechanism. This study justifies the inclusion of this enzyme in many applications for anticancer drug development.
分泌型磷脂酶 A 是具有多种生物学活性的蛇毒蛋白，尤其是抗肿瘤活性。来自同一蛇种但地理位置不同的磷脂酶在生化和生物学活性方面表现出相似性，只是在蛋白质序列上存在微小差异。因此，在先前研究过的毒液中发现具有独特特征的新型磷脂酶 A 可能表明这些差异的起源。在这里，我们从沙特的蛇毒液中分离并鉴定了一种新型 II 组分泌型磷脂酶 A（Cc-PLA-II）。该纯化酶的分子量为 13.945 kDa，在 pH 值为 9.5 和 50°C 时对乳化的磷脂酰胆碱具有 1560 U/mg 的高比活性，且对钙离子有严格的依赖性。有趣的是，在几个 pH 值和温度下孵育酶后，观察到在极端 pH 值和高温下的稳定性。此外，观察到 Cc-PLA 对浓度为 2.5 至 8 µM 的六种人癌细胞系具有显著的剂量依赖性细胞毒性抗肿瘤作用。对正常人脐静脉内皮细胞没有观察到细胞毒性作用。这些结果表明，Cc-PLA-II 除了作为其抗肿瘤机制的一部分具有细胞毒性外，还可能具有血管生成活性。这项研究证明了该酶在许多抗癌药物开发中的应用。
