Department of Chemistry and Biochemistry, North Dakota State University, Fargo, North Dakota 58102, United States.
Coatings and Polymeric Materials Department, North Dakota State University, Fargo, North Dakota 58108, United States.
ACS Appl Mater Interfaces. 2020 Mar 11;12(10):12075-12082. doi: 10.1021/acsami.9b22435. Epub 2020 Feb 26.
Extracting, stabilizing, or delivering biomacromolecules such as proteins and peptides in organic phases have potential applications in biocatalysis, protein extraction, and food antioxidation. However, most current delivery/stabilization platforms face various limitations such as protein/peptide molecular size, platform stability/reusability, and/or potential damage to the cargos. A potential solution to these problems is micellar self-assemblies from amphiphilic invertible polymers, which have recently been demonstrated to be powerful as molecular hosts to deliver both small molecular drugs and functional polypeptides in the aqueous phase. To better understand the function of biomacromolecules and predict the usefulness of the formed invertible micellar assemblies (IMAs) as biomacromolecular hosts in organic phases, it is critical to characterize the spatial distribution, structure, and dynamics of biomacromolecules in the IMA including those upon release. However, the background signals of the IMAs limit the application of most peptide characterization approaches. In this work, we overcome the technical barriers by using site-directed spin labeling electron paramagnetic resonance to probe the spatial arrangement and release of a model, the hemagglutinin (HA) peptide, in the IMAs formed from two different amphiphilic invertible polymers. By site-specifically probing three residues along the peptide chain, for the first time, we depict the possible spatial distribution of HA within the IMAs. By triggering the disassembly of the IMAs with a thermodynamically good solvent (in this study, acetone), we detailed the stability of IMAs in toluene and the peptide release conditions once the polarity of the medium changes. Our findings are important for the application of peptides/proteins at the polar-nonpolar interface or using this interface to extract or deliver biomacromolecules. Our work also demonstrates the power of SDSL-EPR on probing peptide or micelle dynamics, which can be generalized to understand proteins or other biomacromolecules in micellar polymer assemblies in varied applications.
从两亲性可反转聚合物中提取、稳定或输送生物大分子（如蛋白质和肽）在生物催化、蛋白质提取和食品抗氧化等方面具有潜在应用。然而，大多数当前的输送/稳定平台面临着各种限制，如蛋白质/肽分子大小、平台稳定性/可重复使用性和/或对货物的潜在损害。解决这些问题的一个潜在方法是胶束自组装从两亲性可反转聚合物，最近已经证明它们作为小分子药物和功能多肽在水相中的强大分子宿主。为了更好地理解生物大分子的功能，并预测形成的可反转胶束组装体（IMA）作为有机相中的生物大分子宿主的有用性，对 IMA 中生物大分子的空间分布、结构和动力学进行特征描述，包括释放后的情况，这一点至关重要。然而，IMA 的背景信号限制了大多数肽特征分析方法的应用。在这项工作中，我们使用定点自旋标记电子顺磁共振来探测模型、血凝素 (HA) 肽在两种不同两亲性可反转聚合物形成的 IMA 中的空间排列和释放，从而克服了技术障碍。通过在肽链上特异性探测三个残基，我们首次描绘了 HA 在 IMA 内的可能空间分布。通过用热力学良好的溶剂（在本研究中为丙酮）触发 IMA 的解体，我们详细描述了 IMA 在甲苯中的稳定性以及介质极性变化时的肽释放条件。我们的发现对于在极性-非极性界面上应用肽/蛋白质或使用该界面提取或输送生物大分子非常重要。我们的工作还证明了 SDSL-EPR 在探测肽或胶束动力学方面的强大功能，这可以推广到理解不同应用中胶束聚合物组装体中的蛋白质或其他生物大分子。
