Stathi Panagiota, Fotou Evgenia, Moussis Vassilios, Tsikaris Vassilios, Louloudi Maria, Deligiannakis Yiannis
Department of Chemistry, Laboratory of Biomimetic Catalysis & Hybrid Materials, University of Ioannina, Ioannina 4550, Greece.
Department of Chemistry, Laboratory of Protein and Peptide Chemistry, University of Ioannina, Ioannina 4550, Greece.
Langmuir. 2022 Aug 16;38(32):9799-9809. doi: 10.1021/acs.langmuir.2c00710. Epub 2022 Aug 1.
Tyrosine radicals are notoriously short-lived/unstable in solution, while they present an impressive degree of stability and versatility in bioenzymes. Herein, we have developed a library of hybrid biomimetic materials (HBMs), which consists of tyrosine-containing oligopeptides covalently grafted on SiO nanoparticles, and studied the formation, lifetime, and redox properties of tyrosyl radicals. Using electron paramagnetic resonance spectroscopy, we have studied the radical-spin distribution as a probe of the local microenvironment of the tyrosyl radicals in the HBMs. We find that the lifetime of the tyrosyl radical can be enhanced by up to 6 times, by adjusting three factors, namely, a proximal histidine, the length of the oligopeptide, and the interface with the SiO nanomatrix. This is shown to be correlated to a significant lowering of from +736 mV, in free tyrosine, to +548 mV in the {12-peptide}@SiO material. Moreover, we show that grafting on SiO lowers the of tyrosine radicals by ∼50 mV in all oligopeptides. Analysis of the spin-distribution by EPR reveals that the positioning of a histidine at a H-bonding distance from the tyrosine further favors tyrosine radical stabilization.
酪氨酸自由基在溶液中 notoriously 寿命短/不稳定，而它们在生物酶中表现出令人印象深刻的稳定性和多功能性。在此，我们开发了一种杂化仿生材料（HBMs）库，其由共价接枝在SiO纳米颗粒上的含酪氨酸寡肽组成，并研究了酪氨酰自由基的形成、寿命和氧化还原性质。使用电子顺磁共振光谱，我们研究了自由基自旋分布，作为HBMs中酪氨酰自由基局部微环境的探针。我们发现，通过调节三个因素，即近端组氨酸、寡肽长度和与SiO纳米基质的界面，酪氨酰自由基的寿命可提高多达6倍。这表明与从游离酪氨酸中的+736 mV显著降低到{12肽}@SiO材料中的+548 mV相关。此外，我们表明，在所有寡肽中，接枝到SiO上会使酪氨酸自由基的降低约50 mV。通过EPR对自旋分布的分析表明，组氨酸在与酪氨酸的氢键距离处的定位进一步有利于酪氨酸自由基的稳定。
