Metwalli E, Moulin J F, Gebhardt R, Cubitt R, Tolkach A, Kulozik U, Müller-Buschbaum P
Technische Universität München, Physik Department E13, James-Franck-Str.1, 85747 Garching, Germany.
Langmuir. 2009 Apr 7;25(7):4124-31. doi: 10.1021/la802602g.
The water content of casein micelle films in water vapor atmosphere is investigated using time-resolved grazing incidence small-angle neutron scattering (GISANS). Initial dry casein films are prepared with a spin-coating method. At 30 degrees C, the formation of a water-equilibrated casein protein film is reached after 11 min with a total content of 0.36 g of water/g of protein. With increasing water vapor temperature up to 70 degrees C, an increase in the water content is found. With GISANS, lateral structures on the nanometer scale are resolved during the swelling experiment at different temperatures and modeled using two types of spheres: micelles and mini-micelles. Upon water uptake, molecular assemblies in the size range of 15 nm (mini-micelles) are attributed to the formation of a high-contrast D2O outer shell on the small objects that already exist in the protein film. For large objects (>100 nm), the mean size increases at high D2O vapor temperature because of possible aggregation between hydrated micelles. These results are discussed and compared with various proposed models for casein micelle structures.
利用时间分辨掠入射小角中子散射（GISANS）研究了酪蛋白胶束膜在水蒸气气氛中的含水量。采用旋涂法制备初始干酪蛋白膜。在30℃下，11分钟后形成了水合平衡的酪蛋白蛋白膜，水的总含量为0.36 g/ g蛋白质。随着水蒸气温度升高至70℃，发现水含量增加。利用GISANS，在不同温度下的溶胀实验中解析了纳米尺度的横向结构，并使用两种类型的球体进行建模：胶束和微胶束。吸水后，15nm尺寸范围内的分子聚集体（微胶束）归因于蛋白质膜中已存在的小物体上形成了高对比度的D2O外壳。对于大物体（>100nm），由于水合胶束之间可能发生聚集，在高D2O蒸汽温度下平均尺寸会增加。对这些结果进行了讨论，并与各种提出的酪蛋白胶束结构模型进行了比较。
