Pan Yanxiong, Neupane Sunanda, Farmakes Jasmin, Oh Myungkeun, Bentz Kylie, Choi Yongki, Yang Zhongyu
Department of Chemistry and Biochemistry, North Dakota State University, 1231 Albrecht Blvd, Fargo, ND, 58108, USA.
Materials and Nanotechnology Program, North Dakota State University, 51 Batcheller Technology Center, Fargo, ND, 58105, USA.
Chemphyschem. 2018 Mar 5;19(5):651-658. doi: 10.1002/cphc.201701097. Epub 2018 Feb 1.
Protein-polymer conjugates are attractive biomaterials which combine the functions of both proteins and polymers. The bioactivity of these hybrid materials, however, is often reduced upon conjugation. It is important to determine and monitor the protein structure and active site availability in order to optimize the polymer composition, attachment point, and abundance. The challenges in probing these insights are the large size and high complexity in the conjugates. Herein, we overcome the challenges by combining electron paramagnetic resonance (EPR) spectroscopy and atomic force microscopy (AFM) and characterize the structure of antibacterial hybrids formed by polyethylene glycol (PEG) and an antibacterial protein. We discovered that the primary reasons for activity loss were PEG blocking the substrate access pathway and/or altering protein surface charges. Our data indicated that the polymers tended to stay away from the protein surface and form a coiled conformation. The structural insights are meaningful for and applicable to the rational design of future hybrids.
蛋白质-聚合物共轭物是一类具有吸引力的生物材料，它结合了蛋白质和聚合物的功能。然而，这些杂化材料的生物活性在共轭后常常会降低。为了优化聚合物组成、连接点和丰度，确定并监测蛋白质结构和活性位点的可用性很重要。探测这些见解面临的挑战是共轭物的大尺寸和高复杂性。在此，我们通过结合电子顺磁共振（EPR）光谱和原子力显微镜（AFM）克服了这些挑战，并表征了由聚乙二醇（PEG）和一种抗菌蛋白形成的抗菌杂化材料的结构。我们发现活性丧失的主要原因是PEG阻断了底物进入途径和/或改变了蛋白质表面电荷。我们的数据表明，聚合物倾向于远离蛋白质表面并形成卷曲构象。这些结构见解对于未来杂化材料的合理设计具有重要意义且适用。
