A major difference between proteins and surfactants is that proteins are capable of changing their structure during refolding processes in the adsorbed state. It is often reported that these interfacial structure changes increase the surface activity of proteins. In order to investigate this, the surface activity of 5 proteins was determined in foam fractionation experiments, where pH and ionic strength were adjusted separately to gain the maximum surface activity for each protein. Infrared Reflection Absorption Spectroscopy was performed for each protein to analyze the changes in secondary structure after adsorption. In order to investigate quick structural changes, transmission Fourier Transform Infrared spectroscopy was performed to gain information about the secondary structure of the dissolved, non-adsorbed proteins. It was found that most proteins maintain a native-like conformation when adsorbed at the interface. With increasing time, most of the proteins investigated increased the amount of β-sheets at the interface. This slow process went along with a slow increase in surface pressure. A correlation between structural changes on molecular level and surface activity on macroscopic level could not be found. However, the absolute increase of surface pressure at the very beginning of the adsorption process correlated with the surface activity of the proteins, suggesting that the slow processes on molecular level do not have a considerable impact on macroscopic surface activity.

蛋白质和表面活性剂之间的主要区别在于，蛋白质能够在吸附状态的重折叠过程中改变其结构。经常有报道称，这些界面结构的变化会增加蛋白质的表面活性。为了对此进行研究，在泡沫分级实验中测定了 5 种蛋白质的表面活性，其中分别调节 pH 值和离子强度以获得每种蛋白质的最大表面活性。对每种蛋白质进行红外反射吸收光谱分析，分析吸附后二级结构的变化。为了研究快速的结构变化，我们进行了透射傅里叶变换红外光谱，以获取有关溶解的、未吸附的蛋白质的二级结构的信息。发现当吸附在界面上时，大多数蛋白质保持类似天然的构象。随着时间的增加，大多数研究的蛋白质增加了界面处β-折叠的数量。这个缓慢的过程伴随着表面压力的缓慢增加。未发现分子水平的结构变化与宏观水平的表面活性之间的相关性。然而，吸附过程开始时表面压力的绝对增加与蛋白质的表面活性相关，这表明分子水平上的缓慢过程对宏观表面活性没有显着影响。这个缓慢的过程伴随着表面压力的缓慢增加。未发现分子水平的结构变化与宏观水平的表面活性之间的相关性。然而，吸附过程开始时表面压力的绝对增加与蛋白质的表面活性相关，这表明分子水平上的缓慢过程对宏观表面活性没有显着影响。这个缓慢的过程伴随着表面压力的缓慢增加。未发现分子水平的结构变化与宏观水平的表面活性之间的相关性。然而，吸附过程开始时表面压力的绝对增加与蛋白质的表面活性相关，这表明分子水平上的缓慢过程对宏观表面活性没有显着影响。