通过酶学和荧光光谱技术研究神经节苷脂对膜通透性的影响。
Effect of gangliosides on membrane permeability studied by enzymic and fluorescence-spectroscopy techniques.
作者信息
Sarti P, Antonini G, Malatesta F, Vallone B, Brunori M, Masserini M, Palestini P, Tettamanti G
机构信息
Center of Molecular Biology (CNR), University of Rome Tor Vergata, Italy.
出版信息
Biochem J. 1990 Apr 15;267(2):413-6. doi: 10.1042/bj2670413.
The effect of gangliosides on membrane permeability was investigated by studying the kinetic properties of cytochrome c oxidase, the activity of which, when the enzyme is reconstituted in phospholipid vesicles, is dependent on membrane permeability to H+ and K+. The experiments indicate that three different gangliosides (GM1, DD1a, GT1b) incorporated into cytochrome c oxidase-containing phospholipid vesicles stimulate enzymic activity, in the absence of ionophores, most probably by disorganizing the bilayer lipid assembly and increasing its permeability to ions. This interpretation was confirmed by fluorescence-spectroscopy experiments in which the rate of passive leakage of carboxyfluorescein entrapped in the vesicles was measured. Cholera toxin, or its isolated B-subunit, added to GM1-containing proteoliposomes inhibited cytochrome c oxidase activity, indicating the lack of formation, under these experimental conditions, of channels freely permeable to H+ or K+.
通过研究细胞色素c氧化酶的动力学特性来探究神经节苷脂对膜通透性的影响，当该酶在磷脂囊泡中重构时，其活性取决于膜对H⁺和K⁺的通透性。实验表明，三种不同的神经节苷脂（GM1、DD1a、GT1b）掺入含细胞色素c氧化酶的磷脂囊泡中，在无离子载体的情况下刺激酶活性，最有可能是通过破坏双层脂质组装并增加其对离子的通透性。荧光光谱实验证实了这一解释，该实验测量了包裹在囊泡中的羧基荧光素的被动泄漏速率。添加到含GM1的蛋白脂质体中的霍乱毒素或其分离的B亚基抑制了细胞色素c氧化酶活性，表明在这些实验条件下缺乏对H⁺或K⁺自由通透的通道形成。
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