蜂毒肽及其类似物的抗菌活性、溶血活性及与磷脂膜的作用

用CD谱测定了蜂毒肽及其类似物在Tris缓冲液、含2mol/LNaCl的Tris缓冲液和质量分数为10%的六氟异丙醇(HFIP)水溶液中的二级结构.结果表明,蜂毒肽及其类似物在Tris缓冲液中无确定的二级结构.在含2mol/LNaCl的Tris缓冲液中的α-螺旋结构的含量大大增加,表明其形成聚集体.未发现聚集与抗菌活性或溶血活性之间有相关性.在10%HFIP溶液(模拟生物膜环境)中的α-螺旋结构的含量大大增加,表明这些多肽具有内在形成α-螺旋结构的倾向.比较二级结构与抗菌和溶血活性发现,细菌细胞膜促进α-螺旋结构形成的环境比红血球细胞膜和HFIP水溶液强得多,而红血球细胞膜和HFIP水溶液的环境类似.

Antimicrobial and Hemolytic Activities of Melittin and Its Analogues and Their Interactions with Phospholipid Membranes

The secondary structures of melittin and its analogues in Tris buffer, containing 2 mo/L NaCl and 10% hexafluoroisopropanol(HFIP) were determined by CD method. The results showed that melittin and its analogues adopted random coil structures in Tris buffer. The α-helical content of melittin in the buffer containing 2 mol/L NaCl increased markedly, indicating the formation of aggregates, while the analogues did not show a unique conformation. No correlations between the aggregation and antimicrobial or hemolytic activities were found. The α-helical content of melittin and its analogues increased markedly in 10% HFIP, which was widely used to mimic the biomembrane environment in literature, indicating these peptides have an inherent helicity. By comparing the secondary structures and the antimicobial or hemolytic activities, it was found that membranes of bacteria might be a much stronger promoter of α-helical structures than those of erythrocytes and aqueous HFIP, and membranes of erythrocytes has a similar environment with aqueous HFIP.