Adsorption of frog foam nest proteins at the air-water interface
Adsorption of frog foam nest proteins at the air-water interface
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DOI：
10.1529/biophysj.104.046268
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发表时间：
2005-03-01
影响因子：
3.4
通讯作者：
Lu, JR
中科院分区：
文献类型：
--
作者：
Cooper, A;Kennedy, MW;Lu, JR
用表面张力法、双光子激发法研究了热带泡囊蛙泡沫巢蛋白质水溶液的表面活性性质。荧光显微术、镜面中子反射和相关的生物物理技术。Ranaspumins在类似条件下比标准球状蛋白更迅速和更有效地降低水的表面张力。双光子激发。用荧光标记物（苯胺基萘磺酸）处理的巢状泡沫的荧光显微镜显示疏水性蛋白质分配到空气-水界面中，并允许对泡沫结构成像。从利用H2O/D2 O混合物的水的表面的中子反射的测量确定的吸附的蛋白质层的表面过剩，显示出持续增加的表面过剩和层厚度与体浓度。在研究的最高浓度（0.5 mg ml（-1））下，吸附层的特征是有三个不同的区域：一个近似20埃的突出顶层，一个近似30埃的中间层，和一个更扩散的浸没层，向本体溶液中突出约25埃。这表明了一个模型，涉及自组装的蛋白质聚集体在空气-水界面，其中初始泡沫的形成是由特定的表面活性剂蛋白质的混合物，进一步稳定，随后的聚集和交联成一个多层的表面复合物。
The surfactant properties of aqueous protein mixtures ( ranaspumins) from the foam nests of the tropical frog Physalaemus pustulosus have been investigated by surface tension, two-photon excitation. uorescence microscopy, specular neutron reflection, and related biophysical techniques. Ranaspumins lower the surface tension of water more rapidly and more effectively than standard globular proteins under similar conditions. Two- photon excitation. uorescence microscopy of nest foams treated with fluorescent marker ( anilinonaphthalene sulfonic acid) shows partitioning of hydrophobic proteins into the air-water interface and allows imaging of the foam structure. The surface excess of the adsorbed protein layers, determined from measurements of neutron reflection from the surface of water utilizing H2O/D2O mixtures, shows a persistent increase of surface excess and layer thickness with bulk concentration. At the highest concentration studied ( 0.5 mg ml(-1)), the adsorbed layer is characterized by three distinct regions: a protruding top layer of similar to20 Angstrom, a middle layer of similar to30 Angstrom, and a more diffuse submerged layer projecting some 25 Angstrom into bulk solution. This suggests a model involving self-assembly of protein aggregates at the air-water interface in which initial foam formation is facilitated by specific surfactant proteins in the mixture, further stabilized by subsequent aggregation and cross-linking into a multilayer surface complex.