Chiral and molecular recognition between amino acid and sugar molecules and their implications for chemical evolution were investigated using a tandem mass spectrometer equipped with an electrospray ionization source and a cold ion trap. Ultraviolet photodissociation of mass-selected and temperature-controlled gas-phase noncovalent complexes of protonated tryptophan (Trp) and monosaccharide enantiomers, such as aldohexose, aldopentose, and deoxyhexose, was examined as a model for chemical evolution in interstellar molecular clouds. Upon photoexcitation of noncovalent heterochiral H⁺(l-Trp)(d-aldohexose) complexes, NH₂CHCOOH loss from protonated Trp via C_α–C_β bond cleavage occurred. Conversely, in homochiral H⁺(l-Trp)(l-aldohexose), the energy absorbed by Trp was released through the detachment of aldohexose, and dissociation of the amino acid was suppressed. In the photodissociation mass spectra of protonated Trp with aldopentose and deoxyhexose, which lacks the OH group of aldohexose, no dissociation of the molecules in the complexes or differences between enantiomers were observed. These results indicate that the OH groups in monosaccharides contribute to enantiomer-selective photodissociation in molecular clouds. The differences observed between enantiomers in the photodissociation mass spectra were applied to distinguishing and quantifying aldohexose enantiomers in solution using l-Trp as a chiral probe. The enantiomeric excesses of aldohexoses in solution could be determined from a single photodissociation mass spectrum by reference to the relative ion intensities for the NH₂CHCOOH-elimination product and H⁺(l-Trp) formed via detachment of aldohexose. This analysis method could also distinguish and quantify two d-aldohexose mixtures, where l-Trp was employed as an isomer probe.

中文翻译：

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光激发色氨酸在冷气相非共价配合物中对单糖的手性和分子识别，作为星际分子云中化学演化的模型

使用配备有电喷雾电离源和冷离子阱的串联质谱仪，研究了氨基酸和糖分子之间的手性和分子识别及其对化学演化的影响。质子化色氨酸（Trp）和单糖对映异构体（如醛己糖，醛戊糖和脱氧己糖）的质量选择且受温度控制的气相非共价复合物的紫外光解离被研究为星际分子云中化学演化的模型。在非共价异向H的光激发⁺（升-Trp）（d -aldohexose）络合物，NH ₂ CHCOOH损失从质子化的色氨酸通过C _α -C _β发生键断裂。相反，在同手性H ⁺（1- Trp ）（1-醛糖己糖）中，由Trp吸收的能量通过醛糖己糖的释放而释放，并且氨基酸的解离得到抑制。在具有醛糖己糖的OH基团的醛戊糖和脱氧己糖的质子化的Trp的光解质谱中，没有观察到复合物中分子的解离或对映异构体之间的差异。这些结果表明，单糖中的OH基团有助于分子云中对映异构体选择性光解离。在光解质谱对映异构体之间观察到的差异分别适用于区分，并使用在溶液定量对映异构体的己醛糖升-Trp作为手性探针。溶液中的醛糖己糖的对映体过量可通过参考NH ₂ CHCOOH消除产物和通过醛糖己糖的分离形成的H ⁺（1- Trp）的相对离子强度，从单个光解离质谱确定。该分析方法还可以区分和定量两种d-醛糖己糖混合物，其中将1- Trp用作异构体探针。