Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Osaka, 599-8531, Japan.
Department of Chemistry, Graduate School of Science, Osaka Prefecture University, Osaka, 599-8531, Japan.
Anal Biochem. 2021 Apr 15;619:114151. doi: 10.1016/j.ab.2021.114151. Epub 2021 Mar 5.
Chiral recognition between amino acids and monosaccharides in the gas phase was investigated as a model for chemical evolution in interstellar molecular clouds. Ultraviolet (UV) photodissociation spectra and product ion spectra of cold gas-phase hydrogen-bonded clusters of protonated tryptophan (Trp) and a pentose, including ribose and arabinose, were obtained using a tandem mass spectrometer equipped with an electrospray ionization source and a temperature-controlled ion trap. The relative intensity of the signal arising from the S-S transition of protonated Trp observed at approximately 285 nm in the UV photodissociation spectrum of homochiral H(d-Trp)(d-ribose) was significantly higher than that of heterochiral H(l-Trp)(d-ribose), corresponding to the ππ* state of the Trp indole ring. Optical properties of Trp in the clusters induced by 285-nm photoexcitation were applied to the identification and quantification of pentose enantiomers in solution. Pentose enantiomeric excess in solution was determined from relative abundances observed in a single product ion spectrum of 285-nm photoexcited hydrogen-bonded clusters of H(l-Trp) and pentose. A mixture of two pentoses could also be quantified by this method. The geometric and electronic structures of Trp enable recognition of biological molecules through hydrogen bonding.
气相中氨基酸和单糖之间的手性识别被研究为星际分子云中化学进化的模型。采用配备电喷雾电离源和温度控制离子阱的串联质谱仪，获得了质子化色氨酸（Trp）与戊糖（包括核糖和阿拉伯糖）的冷气相氢键簇的紫外（UV）光解光谱和产物离子光谱。在 UV 光解光谱中，观察到大约 285nm 处质子化 Trp 的 S-S 跃迁信号的相对强度，对于同手性 H(d-Trp)(d-核糖)明显高于异手性 H(l-Trp)(d-核糖)，对应于 Trp 吲哚环的 ππ* 态。由 285nm 光激发引起的 Trp 在团簇中的光学性质被应用于溶液中戊糖对映体的鉴定和定量。从 285nm 光激发氢键簇的单个产物离子光谱中观察到的相对丰度确定了溶液中戊糖的对映体过量。通过这种方法还可以定量两种戊糖的混合物。Trp 的几何和电子结构使其能够通过氢键识别生物分子。
