Huang T F, Chiang H S
Pharmacological Institute, College of Medicine, National Taiwan University, Taipei.
Biochim Biophys Acta. 1994 Feb 10;1211(1):61-8. doi: 10.1016/0005-2760(94)90139-2.
By means of gel filtration, ionic exchange chromatography and DEAE-column HPLC, an acidic phospholipase A2 (PLA2) was purified from beaded lizard (Heloderma horridum) venom. The purified PLA is a single-chain polypeptide, consisting of about 163 amino acid residues with a molecular mass of 19,000 Da as calculated by sodium dodecyl sulfate-polyacrylamide gel electrophoresis and amino acid analysis. HHV-PLA showed a rather specific inhibitory effect on platelet aggregation induced by U46619 and epinephrine in human platelet-rich plasma in a dose- and time-dependent manner, whereas it had little effect on collagen- and ADP-induced aggregation. ATP-release reaction induced by various agonists were dose- and time-dependently inhibited by HHV-PLA, even though platelet aggregation was apparently not affected in human washed platelets. When HHV-PLA was chemically modified with p-bromophenacyl bromide, both of its enzymatic activity and antiplatelet activity were lost. Furthermore, exogenous lysophosphatidylcholine and HHV-PLA treated phosphatidylcholine inhibited platelet aggregation induced by U46619 in human washed platelets. In conclusion, PLA enzyme from H. horridum venom inhibits exclusively U46619- or thromboxane-induced platelet aggregation of human platelet-rich plasma probably by virtue of their PLA enzymatic activity on plasma phospholipids, converting phospholipids (e.g., phosphatidylcholine) into lysophospholipids, which in turn interfere with the coupling of TXA2 receptor and its signalling transduction system.
通过凝胶过滤、离子交换色谱法和DEAE柱高效液相色谱法，从珠毒蜥（Heloderma horridum）毒液中纯化出一种酸性磷脂酶A2（PLA2）。纯化后的PLA是一种单链多肽，由约163个氨基酸残基组成，根据十二烷基硫酸钠-聚丙烯酰胺凝胶电泳和氨基酸分析计算，其分子量为19,000 Da。HHV-PLA对富含人血小板血浆中由U46619和肾上腺素诱导的血小板聚集具有相当特异的抑制作用，呈剂量和时间依赖性，而对胶原和ADP诱导的聚集作用很小。HHV-PLA对各种激动剂诱导的ATP释放反应呈剂量和时间依赖性抑制，尽管在人洗涤血小板中血小板聚集明显未受影响。当用对溴苯甲酰溴对HHV-PLA进行化学修饰时，其酶活性和抗血小板活性均丧失。此外，外源性溶血磷脂酰胆碱和经HHV-PLA处理的磷脂酰胆碱抑制人洗涤血小板中由U46619诱导的血小板聚集。总之，珠毒蜥毒液中的PLA酶可能凭借其对血浆磷脂的PLA酶活性，将磷脂（例如磷脂酰胆碱）转化为溶血磷脂，进而干扰TXA2受体与其信号转导系统的偶联，从而专门抑制富含人血小板血浆中由U46619或血栓素诱导的血小板聚集。
