NM Emanuel Institute of Biochemical Physics, Russian Academy of Sciences, Kosygin Str. 4, 119334 Moscow, Russia.
Int J Biol Macromol. 2012 Oct;51(3):319-28. doi: 10.1016/j.ijbiomac.2012.05.012. Epub 2012 May 16.
This work studies the effect of the helix-coil transition in gelatin on the structure development in the complex forming water-gelatin-BSA system using dynamic light scattering, environment scanning electron microscopy, rheometry, differential scanning microcalorimetry, circular dichroism, fluorescence, and absorption measurements. It was established that the structure of the complexes formed and the mechanism of intermacromolecular interaction are different in the case of two conformation states of gelatin. Above the temperature of the conformational transition (40 °C) intermacromolecular interaction leads to collapse gelatin macromolecules and formation compact (30 nm in radius) BSA-gelatin complexes (∼6:1, mole/mole), partial stabilization of the secondary structure (increase the mean helix content), and stabilization of BSA molecules against thermo aggregation. At the same time it does not leads to an appreciable change in the thermodynamic parameters of the thermal transitions for BSA and gelatin. Below the temperature of the conformation transition (at 18 °C) the interaction results in formation of the large (600-1000 nm in radius) complex particles due to trapping BSA molecules into the meshes of the gelatin network and, as consequence, a substantial increase in the storage and loss moduli of the system.
本工作研究了明胶中螺旋-卷曲转变对水-明胶-BSA 体系中复杂结构形成的影响，使用动态光散射、环境扫描电子显微镜、流变学、差示扫描微量热法、圆二色性、荧光和吸收测量。结果表明，在明胶的两种构象状态下，所形成的复合物的结构和分子间相互作用的机制是不同的。在构象转变温度（40°C）以上，分子间相互作用导致明胶大分子的塌陷和形成紧密的（半径 30nm）BSA-明胶复合物（~6:1，摩尔/摩尔），部分稳定二级结构（增加平均螺旋含量），并稳定 BSA 分子免受热聚集。同时，它不会导致 BSA 和明胶的热转变热力学参数发生明显变化。在构象转变温度以下（18°C），由于 BSA 分子被捕获在明胶网络的网格中，相互作用导致形成大的（半径 600-1000nm）复合物颗粒，从而使体系的储能和损耗模量显著增加。
