Center for Biomaterial Development and Berlin-Brandenburg Center for Regenerative Therapies, Helmholtz-Zentrum Geesthacht, Kantstrasse 55, 14513 Teltow, Germany.
Biomacromolecules. 2011 Jan 10;12(1):75-81. doi: 10.1021/bm101029k. Epub 2010 Dec 8.
The single and triple helical organization of protein chains strongly influences the mechanical properties of gelatin-based materials. A chemical method for obtaining different degrees of helical organization in gelatin is covalent functionalization, while a physical method for achieving the same goal is the variation of the drying conditions of gelatin solutions. Here we explored how the introduction of desaminotyrosine (DAT) and desaminotyrosyl tyrosine (DATT) linked to lysine residues of gelatin influenced the kinetics and thermodynamic equilibrium of the helicalization process of single and triple helices following different drying conditions. Drying at a temperature above the helix-to-coil transition temperature of gelatin (T > T(c), called v(short)) generally resulted in gelatins with relatively lower triple helical content (X(c,t) = 1-2%) than lower temperature drying (T < T(c), called v(long)) (X(c,t) = 8-10%), where the DAT(T) functional groups generally disrupted helix formation. While different helical contents affected the thermal transition temperatures only slightly, the mechanical properties were strongly affected for swollen hydrogels (E = 4-13 kPa for samples treated by v(long) and E = 120-700 kPa for samples treated by v(short)). This study shows that side group functionalization and different drying conditions are viable options to control the helicalization and macroscopic properties of gelatin-based materials.
蛋白质链的单螺旋和三螺旋结构强烈影响基于明胶的材料的机械性能。获得明胶中不同程度的螺旋结构的化学方法是共价官能化，而实现相同目标的物理方法是改变明胶溶液的干燥条件。在这里，我们探讨了引入与赖氨酸残基连接的去氨酪氨酸（DAT）和去氨酪氨酸基酪氨酸（DATT）如何影响单螺旋和三螺旋螺旋化过程的动力学和热力学平衡，遵循不同的干燥条件。在明胶的螺旋-无规卷曲转变温度（T > T(c)，称为 v(short))以上的温度下干燥通常导致具有相对较低的三螺旋含量（X(c,t) = 1-2%）的明胶，而低于温度干燥（T < T(c)，称为 v(long))（X(c,t) = 8-10%），其中 DAT(T) 官能团通常破坏螺旋形成。虽然不同的螺旋含量仅略微影响热转变温度，但机械性能受到强烈影响，对于溶胀水凝胶（用 v(long)处理的样品的 E = 4-13 kPa 和用 v(short)处理的样品的 E = 120-700 kPa）。这项研究表明，侧基官能化和不同的干燥条件是控制基于明胶的材料的螺旋化和宏观性质的可行选择。
