TU Dortmund University, Department of Chemistry and Chemical Biology, D-44221 Dortmund, Germany.
TU Dortmund University, Department of Chemistry and Chemical Biology, D-44221 Dortmund, Germany.
Colloids Surf B Biointerfaces. 2017 Oct 1;158:9-15. doi: 10.1016/j.colsurfb.2017.06.030. Epub 2017 Jun 21.
Responsive interfaces are often realized by polymer films that change their structure and properties upon changing the pH-value, ionic strength or temperature. Here, we present a bioresponsive interfacial structure that is based on a protein, calmodulin (CaM), which undergoes a huge conformational change upon ligand binding. At first, we characterize the conformational functionality of a double Cys mutant of CaM by small-angle X-ray scattering (SAXS) and Fourier transform infrared (FTIR) spectroscopy. The CaM mutant is then used to cross-link poly(ethylene glycol) (PEG) chains, which are bound covalently to a supporting planar Si surface. These films are characterized by X-ray reflectometry (XR) in a humidity chamber providing full hydration. It is well known that Ca-saturated holo-CaM binds trifluoperazine (TFP) and changes its conformation from an open, dumbbell-shaped to a closed, globular one in solution. At the interface, we observe an increase of the PEG-CaM film thickness, when TFP is binding and inducing the closed conformation, whereas the removal of Ca-ions and a concomitant release of TFP is associated with a decrease of the film thickness. This toggling of the film thickness is largely reversible. In this way, a structural change of the interface is achieved via protein functionality which has the advantage of being selective for ligand molecules without changing the environmental conditions in a harsh way via physico-chemical parameters.
响应性界面通常通过聚合物薄膜来实现，这些聚合物薄膜在 pH 值、离子强度或温度发生变化时会改变其结构和性质。在这里，我们提出了一种基于蛋白质钙调蛋白（CaM）的生物响应性界面结构，当配体结合时，钙调蛋白会发生巨大的构象变化。首先，我们通过小角 X 射线散射（SAXS）和傅里叶变换红外（FTIR）光谱来表征 CaM 双半胱氨酸突变体的构象功能。然后，将 CaM 突变体用于交联聚乙二醇（PEG）链，PEG 链通过共价键结合到支撑的平面 Si 表面上。这些薄膜在湿度室中的 X 射线反射计（XR）中进行了表征，提供了完全水合的条件。众所周知，Ca 饱和的全钙调蛋白结合三氟拉嗪（TFP），并在溶液中从开放的哑铃形构象转变为闭合的球形构象。在界面上，当 TFP 结合并诱导闭合构象时，我们观察到 PEG-CaM 薄膜厚度增加，而 Ca 离子的去除和 TFP 的伴随释放与薄膜厚度的减少有关。这种薄膜厚度的切换在很大程度上是可逆的。通过这种方式，通过蛋白质功能实现了界面的结构变化，这种方法的优点是对配体分子具有选择性，而不会通过物理化学参数以苛刻的方式改变环境条件。
