An important form of biological sulfur is sulfane sulfur, or S⁰, which is found in polysulfide and persulfide compounds as well as in elemental sulfur. Sulfane sulfur, often in the form of S₈, functions as a key energy source in the metabolic processes of thermophilic Archaean organisms found in sulfur-rich environments and can be metabolized both aerobically and anaerobically by different archaeons. Despite this importance, S₈ has a low solubility in water (∼19 nM), raising questions of how it can be made chemically accessible in complex environments. Motivated by prior crystallographic data showing S₈ binding to hydrophobic motifs in filamentous glycoproteins from the sulfur reducing Staphylothermus marinus anaerobe, we demonstrate that simple macrocyclic hydrophobic motifs, such as 2-hydroxypropyl β-cyclodextrin (2HPβ), are sufficient to solubilize S₈ at concentrations up to 2.0 ± 0.2 mM in aqueous solution. We demonstrate that the solubilized S₈ can be reduced with the common reductant tris(2-carboxyethyl)phosphine (TCEP) and reacts with thiols to generate H₂S. The thiol-mediated conversion of 2HPβ/S₈ to H₂S ranges from 80% to quantitative efficiency for Cys and glutathione (GSH). Moreover, we demonstrate that 2HPβ can catalyze the Cys-mediated reduction of S₈ to H₂S in water. Adding to the biological relevance of the developed systems, we demonstrate that treatment of Raw 264.7 macrophage cells with the 2HPβ/S₈ complex prior to LPS stimulation decreases NO₂⁻ levels, which is consistent with known activities of bioavailable H₂S and sulfane sulfur. Taken together, these investigations provide a new strategy for delivering H₂S and sulfane sulfur in complex systems and more importantly provide new insights into the chemical accessibility and storage of S⁰ and S₈ in biological environments.

中文翻译：

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改性环糊精可溶解水中的元素硫并实现生物硫磺的输送

生物硫的一种重要形式是硫丹，即S ⁰，它存在于多硫化物和过硫化物以及元素硫中。硫磺（通常为S ₈形式）是在富含硫的环境中发现的嗜热古生生物代谢过程中的关键能源，可以通过不同的古生菌进行需氧和厌氧代谢。尽管具有这种重要性，S ₈在水中的溶解度很低（〜19 nM），这引发了人们对如何使其在复杂环境中化学可及性的疑问。由先前的晶体学数据表明，S ₈与硫减少的葡萄球菌的丝状糖蛋白中的疏水基序结合厌氧菌，我们证明了简单的大环疏水基序，例如2-羟丙基β-环糊精（2HPβ），足以在水溶液中以高达2.0±0.2 mM的浓度溶解S ₈。我们表明，溶解的小号₈可以与共同还原剂可以减少三（2-羧乙基）膦（TCEP）并反应与硫醇以产生H ₂ S的2HPβ的硫醇介导的转化/ S ₈至H ₂期从范围半胱氨酸和谷胱甘肽（GSH）定量效率的80％。此外，我们证明了2HPβ可以催化Cys介导的S ₈还原为H ₂S在水中。添加到开发的系统的生物相关性，我们表明，治疗原始的264.7巨噬细胞用2HPβ/ S ₈复杂之前LPS刺激减少NO ₂ ^-的水平，这是与生物可利用的H的已知活性一致₂ S和硫烷硫。综上所述，这些研究提供了在复杂系统中输送H ₂ S和硫烷硫的新策略，更重要的是，它为生物环境中S ⁰和S ₈的化学可及性和储存提供了新的见解。