INTERACTION OF S-100 PROTEIN WITH CATIONS AND LIPOSOMES
INTERACTION OF S-100 PROTEIN WITH CATIONS AND LIPOSOMES
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DOI：
10.1021/bi00719a013
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发表时间：
1974-01-01
期刊：
影响因子：
2.9
通讯作者：
FASELLA, P
中科院分区：
文献类型：
--
作者：
CALISSANO, P;ALEMA, S;FASELLA, P
研究了脑特异性蛋白S-100与Ca ~（2+）、K ~+和人工脂质膜（脂质体）的相互作用。S-100蛋白有两组Ca ~（2+）结合位点，在60 mM Tris-HCl缓冲液（pH7.6和22）中，解离常数分别为~（10）× 10 ~（-5）和~（10）× 10~（-3）M。在K ~+存在下，Ca ~（2+）与高亲和力位点结合引起构象变化，引起蛋白质内在荧光增加，使蛋白质能与Rb ~+相互作用。最近发现脑特异性蛋白S-100能与脂质膜（脂质体）相互作用，并引起脂质膜对Rb ~+的通透性增加（Calissano和Bangham，1971）。脂质体是由包围水相的两个或更多个脂质层形成的液晶（Bangham等人，1965年）。它们已被用作生物膜的模型，以研究几种物质（抗生素，蛋白质等）的作用。离子渗透性。S-100诱导的效应需要Ca 2+的存在，并且随着脂质膜的组成而变化，用由磷脂酰丝氨酸和磷脂酰胆碱组成的带负电荷的脂质体观察到最大的效应。关于这种诱导扩散的机制的简单假设是基于S-100和Ca 2+离子之间的良好建立的相互作用（Calissano等人，1969年）。这种阳离子与蛋白质的结合伴随着某些疏水性氨基酸残基暴露于溶剂。Ca ~（2+）可促进细胞与细胞间的相互作用。
The interaction of the brain-specific protein S-100 with Ca2+, K+, and artificial lipid membranes (lipo-somes) was studied. The protein S-100 has two sets of Ca2+ binding sites with dissociation constants which, in 60 mM Tris-HCl buffer (pH 7.6 and 22), are, respectively,=¡ 5 X 10-5 and 1 X 10~ 3 M. In the presence of K+ the binding of Ca2+ to the high affinity sites induces a conformational change which causes an increase of the protein intrinsic flu-orescence and makes the protein capable of interacting withThe brain-specific protein S-100 has been recently shown to interact with lipid membranes (liposomes) and to induce an increase in their permeability to Rb+(Calissano and Bangham, 1971). Liposomes are liquid crystals formed by two or more lipid layers surrounding an aqueous phase (Bangham et al., 1965). They have been used as a model of biological membranesto investigate the effect of several substances (antibiotics, proteins, etc.) on ion permeability. The effect induced by S-100 requires the presence of Ca2+ and varies with the composition of the lipid membrane, the largest effect being observed with negatively charged lipo-somes, consisting of phosphatidylserine and phosphatidylcholine. A simple hypothesis on the mechanism of this in-duced diffusion was based on the well-established interaction between S-100 and Ca2+ ions (Calissano et al., 1969). The binding of this cation to the protein is accompanied by the exposure to the solvent of some hydrophobic amino acid residues. Ca2+ would facilitate the interaction between the