School of Biological Sciences, University of Northern Colorado, 501 20th St., CB 92, Greeley, CO 80639-0017, USA.
Toxicon. 2010 Jul;55(8):1463-74. doi: 10.1016/j.toxicon.2010.02.028. Epub 2010 Mar 12.
The Western Rattlesnake (Crotalus viridis sensu lato, now including Crotalus oreganus) is broadly distributed across the western half of the United States, northwestern Mexico and southwestern Canada, and eight subspecies are currently recognized. Although some venom characteristics have been noted for most subspecies, a systematic study of venoms from all subspecies has not been reported. Venom was extracted from snakes collected from approximate geographic range centers for all subspecies and analyzed using SDS-PAGE, MALDI-TOF mass spectrometry, enzyme and toxicity assays. Electrophoretic and mass spectrometric analyses demonstrated that small myotoxins, disintegrins and PLA(2) were abundant in most venoms. PIII and PI metalloproteinases ( approximately 54 kDa and 23 kDa, respectively) were common to all venoms except C. o. concolor, C. o. caliginis and C.o. helleri. Metalloproteinase activity was highest in C. o. cerberus and lowest in C. o. concolor venoms ( approximately 100-fold difference). Conversely, C. o. concolor venom was the most toxic and C. o. cerberus venom was least toxic (15-fold difference). In general, venoms with high metalloproteinase activity were less toxic (type I venoms), while venoms which were highly toxic showed low protease activity (type II venoms). Within the C. viridis/oreganus complex, these two extremes of venom compositional phenotypes are observed, and it appears that high metalloproteinase activity and high toxicity are incompatible qualities of these venoms. The functional significance of these biochemical characteristics likely relates to characteristics of prey consumed, and venoms with low metalloproteinase activity may constrain snake prey selection or foraging activity patterns.
响尾蛇（广义的 Crotalus viridis sensu lato，包括现在的 Crotalus oreganus）广泛分布于美国西部、西北墨西哥和西南加拿大，目前已确认有 8 个亚种。尽管大多数亚种的毒液特性已经被注意到，但尚未有对所有亚种毒液的系统研究报告。从所有亚种的地理分布中心采集蛇类并提取毒液，使用 SDS-PAGE、MALDI-TOF 质谱、酶和毒性测定进行分析。电泳和质谱分析表明，大多数毒液中含有丰富的小肌肉毒素、分裂素和 PLA2。除 C. o. concolor、C. o. caliginis 和 C.o. helleri 外，所有毒液中均含有 PIII 和 PI 金属蛋白酶（分别约为 54 kDa 和 23 kDa）。除 C. o. cerberus 外，所有毒液中均含有金属蛋白酶活性最高的 C. o. concolor 毒液（约相差 100 倍）。相反，C. o. concolor 毒液毒性最高，C. o. cerberus 毒液毒性最低（相差 15 倍）。一般来说，具有高金属蛋白酶活性的毒液毒性较低（I 型毒液），而具有高毒性的毒液蛋白酶活性较低（II 型毒液）。在 C. viridis/oreganus 复合体中，观察到这两种毒液组成表型的极端情况，似乎高金属蛋白酶活性和高毒性是这些毒液不相容的性质。这些生化特性的功能意义可能与猎物的特征有关，低金属蛋白酶活性的毒液可能会限制蛇类对猎物的选择或觅食活动模式。
