Domain structure and molecular conformation in annexin V/1,2-dimyristoyl-sn-glycero-3-phosphate/Ca2+ aqueous monolayers: a Brewster angle microscopy/infrared reflection-absorption spectroscopy study.
Domain structure and molecular conformation in annexin V/1,2-dimyristoyl-sn-glycero-3-phosphate/Ca2+ aqueous monolayers: a Brewster angle microscopy/infrared reflection-absorption spectroscopy study.
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膜联蛋白 V/1,2-二肉豆蔻酰-sn-甘油-3-磷酸/Ca2 水单层中的结构域结构和分子构象：布鲁斯特角显微镜/红外反射吸收光谱研究。
DOI：
10.1016/s0006-3495(98)78034-8
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发表时间：
1998
影响因子：
3.4
通讯作者：
Mendelsohn,R
中科院分区：
文献类型：
--
作者：
Wu,F;Gericke,A;Flach,CR;Mealy,TR;Seaton,BA;Mendelsohn,R
膜联蛋白包括一个蛋白质家族，表现出Ca2+依赖性结合磷脂膜，这可能与其体内功能有关。虽然关于三元（蛋白质/脂质/Ca2+）在体相中的相互作用的大量结构信息已经从各种技术中得到，但对三元单层膜的时间和空间组织知之甚少。因此，Ca2+对膜联蛋白V （AxV）和阴离子DMPA单层之间相互作用的影响通过三种互补的方法进行了研究：表面压力测量、红外反射吸收光谱（IRRAS）和布鲁斯特角度显微镜（BAM）。在没有Ca2+的情况下，将AxV注射到DMPA单层下的水亚相中，产生BAM图像，显示可能被液体膨胀的脂质包围的蛋白质结构域。富含蛋白质的区域随着时间的推移而扩大，导致DMPA可用的面积减少，并最终在与蛋白质膜分离的空间区域形成凝聚脂质结构域。因此，没有证据表明AxV/脂质有特异性的二元相互作用。相比之下，在总Ca2+浓度为10μM时，在DMPA单层下注射AxV/Ca2+，没有发现纯蛋白结构域，而是缓慢形成针头结构。随后是整个膜的缓慢（bbb2h）硬化，伴随着表面压力的增加，固体域的连接形成类似珍珠串的结构。这些变化是这种特殊三元相互作用的特征。在2850cm−1附近用ν symch22测量的DMPA的酰基链构象顺序，与单独的DMPA单层或Ca2+存在时相比，AxV/DMPA和AxV/DMPA/Ca2+单层中DMPA的酰基链构象顺序都增加了。从这项工作中可以明显看出，从这三种互补技术中获得的结构和时间信息的组合，可以用于研究空气/水界面上的原位单层。
Annexins comprise a family of proteins that exhibit a Ca2+-dependent binding to phospholipid membranes that is possibly relevant to their in vivo function. Although substantial structural information about the ternary (protein/lipid/Ca2+) interaction in bulk phases has been derived from a variety of techniques, little is known about the temporal and spatial organization of ternary monolayer films. The effect of Ca2+on the interactions between annexin V (AxV) and anionic DMPA monolayers was therefore investigated using three complementary approaches: surface pressure measurements, infrared reflection-absorption spectroscopy (IRRAS), and Brewster angle microscopy (BAM). In the absence of Ca2+, the injection of AxV into an aqueous subphase beneath a DMPA monolayer initially in a liquid expanded phase produced BAM images revealing domains of protein presumably surrounded by liquid-expanded lipid. The protein-rich areas expanded with time, resulting in reduction of the area available to the DMPA and, eventually, in the formation of condensed lipid domains in spatial regions separate from the protein film. There was thus no evidence for a specific binary AxV/lipid interaction. In contrast, injection of AxV/Ca2+at a total Ca2+concentration of 10μM beneath a DMPA monolayer revealed no pure protein domains, but rather the slow formation of pinhead structures. This was followed by slow (>2h) rigidification of the whole film accompanied by an increase in surface pressure, and connection of solid domains to form a structure resembling strings of pearls. These changes were characteristic of this specific ternary interaction. Acyl chain conformational order of the DMPA, as measured byνsymCH2near 2850cm−1, was increased in both the AxV/DMPA and AxV/DMPA/Ca2+monolayers compared to either DMPA monolayers alone or in the presence of Ca2+. The utility of the combined structural and temporal information derived from these three complementary techniques for the study of monolayers in situ at the air/water interface is evident from this work.