Fusion of sphingomyelin vesicles induced by proteins from Taiwan cobra (Naja naja atra) venom. Interactions of zwitterionic phospholipids with cardiotoxin analogues.
Fusion of sphingomyelin vesicles induced by proteins from Taiwan cobra (Naja naja atra) venom. Interactions of zwitterionic phospholipids with cardiotoxin analogues.
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台湾眼镜蛇 (Naja naja atra) 毒液蛋白质诱导的鞘磷脂囊泡融合。
DOI：
10.1016/s0021-9258(18)49982-6
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发表时间：
1991
期刊：
影响因子：
--
通讯作者：
W. Wu
中科院分区：
文献类型：
--
作者：
K. Chien;W. N. Huang;J. Jean;W. Wu
为了避免纯化过程中磷脂酶A2的污染，采用卵鞘磷脂囊泡法测定了中华眼镜蛇毒蛋白的聚集/融合活性。它导致了一种新的心脏毒素（CTX）类似物蛋白（CTX V）的鉴定，主要聚集/融合，但很少溶血，活动。与此相反，心脏毒素（CTX III）诱导显着的人红细胞的溶血，但表现出很少的聚集/融合活动。为了研究这些CTX诱导的过程的结构/活性关系，CTX V的氨基酸序列进行了测定，并通过透射电子显微镜，准弹性激光光散射，差示扫描量热法和荧光光谱与CTX III的聚集/融合活性进行了比较。结果表明，在略高于鞘磷脂囊泡的凝胶至液晶相变的温度下的CTX诱导的融合过程可以最终将小的超声处理的囊泡转化为尺寸为1-2微米的大的融合囊泡。CTX V诱导鞘磷脂囊泡内容物泄漏和引起囊泡融合的能力比CTX III高约10倍。基于本研究和其他研究中确定的CTX结构，建议高度保守的序列-Cys-Pro-X-Gly-Lys-Gln-Leu-Cys-中的氨基酸残基X在CTX与脂质分子的相互作用中起作用。脂质相转变可以进一步增强囊泡融合过程中的蛋白质-脂质相互作用。
Egg sphingomyelin vesicles were used to assay aggregation/fusion activities of proteins from Taiwan (Naja naja atra) venom to avoid the problem of phospholipase A2 contamination during protein purification. It led to the identification of a new cardiotoxin (CTX) analogue protein (CTX V) with major aggregation/fusion, but few hemolysis, activities. On the contrary, cardiotoxin (CTX III) induced significant hemolysis of human red blood cells but exhibited few aggregation/fusion activities. To study the structure/activity relationship of these CTX-induced processes, the amino acid sequence of CTX V was determined and its aggregation/fusion activity was compared with that of CTX III by transmission electron microscopy, quasielastic laser light scattering, differential scanning calorimetry, and fluorescence spectroscopy. The results show that the CTX-induced fusion process at temperatures slightly above that of the gel to liquid-crystalline phase transition of sphingomyelin vesicles can ultimately convert small sonicated vesicles into large fused vesicles with sizes of 1-2 microns. The abilities of CTX V to induce the leakage of sphingomyelin vesicles content and to cause the fusion of vesicles are approximately 10-fold higher than those of CTX III. Based on the CTX structures determined in the present and other studies, it is suggested that the amino acid residue X within the well conserved sequence of -Cys-Pro-X-Gly-Lys-Gln-Leu-Cys- plays a role in the interaction of CTX with lipid molecules. The lipid phase transition could further enhance the protein-lipid interaction in the process leading to the fusion of vesicles.