Department of Physics and Randall Division of Cell and Molecular Biophysics, King's College London, WC2R 2LS London, UK.
Centre of Excellence for Mass Spectrometry, King's College London, SE5 8AF London, UK.
Nat Commun. 2017 Jun 6;8:15658. doi: 10.1038/ncomms15658.
The nanomechanical properties of elastomeric proteins determine the elasticity of a variety of tissues. A widespread natural tactic to regulate protein extensibility lies in the presence of covalent disulfide bonds, which significantly enhance protein stiffness. The prevalent in vivo strategy to form disulfide bonds requires the presence of dedicated enzymes. Here we propose an alternative chemical route to promote non-enzymatic oxidative protein folding via disulfide isomerization based on naturally occurring small molecules. Using single-molecule force-clamp spectroscopy, supported by DFT calculations and mass spectrometry measurements, we demonstrate that subtle changes in the chemical structure of a transient mixed-disulfide intermediate adduct between a protein cysteine and an attacking low molecular-weight thiol have a dramatic effect on the protein's mechanical stability. This approach provides a general tool to rationalize the dynamics of S-thiolation and its role in modulating protein nanomechanics, offering molecular insights on how chemical reactivity regulates protein elasticity.
弹性蛋白的纳米力学性质决定了各种组织的弹性。一种广泛存在的调节蛋白质伸展性的自然策略是存在共价二硫键，这显著增强了蛋白质的硬度。在体内形成二硫键的流行策略需要存在专门的酶。在这里，我们提出了一种替代的化学途径，通过基于天然存在的小分子的二硫键异构化来促进非酶促氧化蛋白质折叠。使用单分子力钳光谱法，结合 DFT 计算和质谱测量，我们证明了蛋白质半胱氨酸和攻击的低分子量巯基之间瞬态混合二硫键中间加合物的化学结构的细微变化对蛋白质的机械稳定性有显著影响。这种方法为合理化 S-硫醇化的动力学及其在调节蛋白质纳米力学中的作用提供了一种通用工具，为化学反应性如何调节蛋白质弹性提供了分子见解。
