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目的 :了解具杀菌活性的哺乳生物血小板型磷脂酶 A2 (PL A2 )分子进化的特点。方法 :将所有已知哺乳生物的血小板型和胰腺型 PL A2 的 c DNA和基因资料进行收集并加以统计和分析。结果 :哺乳生物血小板型 PL A2 基因突变的频率较胰腺型 PL A2 高 ,碱基取代中非同义取代数高于同义取代数。血小板型 PL A2 的蛋白质结构中可形成对酸不稳定的肽键的氨基酸明显较少 ,而易被发酵产物乙酰基不可逆化学修饰的精氨酸明显高于胰腺型。结论 :血小板型 PL A2 的进化速度相对较快 ,其进化的压力有二 :1形成对酸稳定的结构 ;2离开了易产生乙酰基而修饰精氨酸的环境。其结果使血小板型 PL A2 形成带较多正电荷的碱性分子 ,具有了杀菌活性。
Objective: To understand the molecular evolution of mammalian platelet-derived phospholipase A2 (PL A2) with bactericidal activity. METHODS: The c DNA and genomic data of all known mammalian platelet and pancreatic PL A2 were collected and statistically analyzed. RESULTS: The frequency of PL A2 gene mutation in mammalian platelets was higher than that of pancreatic PL A2. The number of non-synonymous substitutions in base substitutions was higher than that in synonymous substitutions. In the protein structure of platelet-type PL A2, there are significantly fewer amino acids that can form acid-labile peptide bonds, while arginine, which is easily chemically modified by the acetyl group of the fermentation product, is significantly higher than that of the pancreas. CONCLUSION: Platelet-derived PL A2 evolves relatively rapidly with two evolutionary pressures: 1 forming an acid-stable structure; 2 leaving an environment that is susceptible to acetyl groups and modifying arginine. As a result, platelet-type PL A2 forms a basic molecule with more positive charges and has bactericidal activity.