Molecular interaction mechanism and structure–activity relationships of protein–polyphenol complexes revealed by side-directed spin labeling-electron paramagnetic resonance (SDSL-EPR) spectroscopy
2023
Li, Hui | Pan, Yanxiong | Lan, Yang | Yang, Zhongyu | Rao, Jiajia | Chen, Bingcan
Deciphering interactions between bioactive protein and polyphenols are critical for designing and controlling functional protein–polyphenol complexes. Herein, using the site-directed spin labeled T4 lysozyme (T4L) and rosmarinic acid (RA) as a model system, we combined electron paramagnetic resonance spectra to investigate molecular interaction mechanism of the protein–polyphenol complexes in structural or conformational details. Experimental results show that molecular interactions between T4L and RA are a process from order to disorder. TEM images display that the complexes finally assemble into quasi-spherical colloidal particles. When T4L/RA ratio is 1:1, the complexes exhibit the optimized enzymatic and antioxidant dual-functionalities due to the synergetic effect and protection mechanism. However, with excess addition of RA, the enzymatic and antioxidant activities of the complexes started to attenuate because the catalytic active site and bioactive hydroxyl groups were buried. The revealed high-resolution interaction process could help better understand the corresponding alterations between structure and functionalities.
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