Tampé R, Galla H J
Institute of Biochemistry, Technical University Darmstadt, Federal Republic of Germany.
Eur J Biochem. 1991 Jul 1;199(1):187-93. doi: 10.1111/j.1432-1033.1991.tb16108.x.
Glycophorin has been reconstituted into egg phosphatidylethanolamine (egg-PtdEtn) membranes. Stable vesicles were obtained at a molar ratio of 8 x 10(-4) of inserted protein/lipid. This macroscopic change from lipid aggregates to lipid vesicles was followed by density gradient centrifugation. Vesicles formed in the presence of protein enclose the dye calcein and are stable with time and temperature. Membrane aggregation does not occur, as was demonstrated by energy-transfer experiments. The phase transition from the fluid lamellar L alpha phase to the inverted hexagonal HII phase observed at 29 degrees C in pure egg-PtdEtn membranes is suppressed and finally disappears in the presence of glycophorin. The transition enthalpy decreases linearly from delta H = 4 kJ/mol in pure lipids to zero at a protein/lipid molar ratio of 1:1000. Ca2+ ions and wheat germ lectin act synergistically on the phase behavior of vesicles containing glycophorin and phosphatidylethanolamine. Differential scanning calorimetry scans show that the lamellar-to-hexagonal phase transition is reinduced. The membranes aggregate and exchange lipid as could be demonstrated by energy transfer experiments. The dye calcein is released but only if the temperature exceeds the lamellar-to-hexagonal phase transition temperature of the pure egg-PtdEtn.
血型糖蛋白已被重组到鸡蛋磷脂酰乙醇胺（egg-PtdEtn）膜中。以插入蛋白/脂质摩尔比为8×10⁻⁴可获得稳定的囊泡。通过密度梯度离心追踪了从脂质聚集体到脂质囊泡的这种宏观变化。在蛋白存在下形成的囊泡包裹着荧光素，并且随时间和温度保持稳定。如能量转移实验所示，未发生膜聚集。在纯egg-PtdEtn膜中于29℃观察到的从流体层状Lα相到反相六角形HII相的相变受到抑制，在血型糖蛋白存在下最终消失。转变焓从纯脂质中的ΔH = 4 kJ/mol线性降低至蛋白/脂质摩尔比为1:1000时的零。Ca²⁺离子和麦胚凝集素对含血型糖蛋白和磷脂酰乙醇胺的囊泡的相行为具有协同作用。差示扫描量热法扫描表明重新诱导了层状到六角形的相变。如能量转移实验所示，膜发生聚集并交换脂质。荧光素被释放，但仅当温度超过纯egg-PtdEtn的层状到六角形的相变温度时才会释放。
