电中性解吸质谱法对中性丝氨酸八聚体手性传递机制的研究

The homochirality of basic biological molecules is of prime importance to the origin of life. Neutral serine octamer (Ser8) is of particular interest in this respect because of the strongly preferred homochirality. However, identifying serine octamer as either neutral or protonated by mass spectrometry is difficult, which makes the chiral transfer mechanism is still unclear. In this project, field-free desorption mass spectrometry is developed, in which field-free desorption of serine solution while residual protonated octamer is electrically deflected in gas phase, which guarantees that only neutral Ser8 undergoes the subsequent on-line protonation without interference from protonated octamer. With this setup, the formation and fragmentation of the neutral Ser8 are studied to provide information for molecular structure. The chiral selection reaction between neutral Ser8 and biomolecules, as well as the interaction between neutral Ser8 and inorganic compounds/ions, are also investigated. The reaction products are identified and further summarized to elucidate the chiral transfer mechanism of neutral Ser8 in the origin of life. The field-free desorption mass spectrometry using nebulization without the use of high voltage greatly maintains the original state of target analytes, which offers a reliable method for mass spectrometry in identifying existence form (neutral or charged) of target analyte. This research will reveal the chiral transfer mechanism of neutral Ser8, and further offer significant information for understanding the evolution of life which shows high homochirality.

生命起源与生物分子的手性均一性相关，中性丝氨酸八聚体具有显著的手性均一性，其手性传递对揭示组成生命体的分子表现出单一手性具有重要科学意义。然而，现有质谱技术无法识别丝氨酸八聚体以中性或质子化形式存在，致使其手性传递机制尚不明确。本项目以自主开发的电中性解吸质谱技术为基础，在气相中采用偏转电场去除质子化丝氨酸八聚体，分离出中性丝氨酸八聚体，进而研究其形成和碎裂特征，为分子结构研究提供理论依据；深入研究中性丝氨酸八聚体与生物分子的对映取代反应，以及与无机物质的反应，鉴别反应产物，归纳总结反应特征，揭示中性丝氨酸八聚体在生命起源过程中的手性传递机制。本项目为质谱识别目标物以中性分子或离子状态存在提供一种新方法，突破质子化丝氨酸八聚体干扰的瓶颈，旨在解决中性丝氨酸八聚体在生命起源过程中手性传递机制不明确的问题，为阐明组成生命体的分子表现出单一手性提供理论依据。

生命前化学是阐明生命起源中有机小分子向生物大分子转化的重要环节，对阐明生命物质的起源具有重要科学意义。本项目针对早期关键生命物质的起源以及传递规律，开发了电中性解吸质谱法，其采用气动雾化，无高压作用于样品溶液，形成的喷雾为电中性微液滴，维持了样品的原始状态，为鉴别样品中目标物以何种形式（中性、离子等）存在提供一种简单、可靠的新方法。采用电中性解吸质谱法分离和解析了中性丝氨酸八聚体的形成特征和结构，研究了中性丝氨酸八聚体与不同构型生物分子（氨基酸、葡萄糖等）对映体的选择反应，研究了中性丝氨酸八聚体与无机物质（磷酸、金属离子等）相互作用关系，阐明了中性丝氨酸八聚体的手性传递机制。在此基础上，采用电中性解析质谱法中形成的中性微液滴，合成了早期关键物质（多肽、核酸、磷脂等）以及早期物质循环的关键代谢网络还原性三羧酸循环。采用电中性质谱法，还捕捉和分离了反应过程中的关键中间体，为化学反应机理提供了理论基础。采用电中性解析质谱法中中性喷雾方式与等离子体结合，开发了电中性雾化等离子体质谱法，实现了非极性物质的灵敏、快速分析。共发表本基金标注的SCI论文12篇，其中通讯或第一作者SCI论文通讯或第一作者论文10篇，申请相关发明专利2项。

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