Amino Acids ( IF 3.0 ) Pub Date : 2020-07-24 , DOI: 10.1007/s00726-020-02875-8 Soma Hanaichi 1 , Akimasa Fujihara 1
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Abstract
The molecular recognition ability of tryptophan (Trp) for isomeric amino acids, such as leucine (Leu) and isoleucine (Ile), and isomeric amino acid-containing dipeptides, such as Leu-Gly, Ile-Gly, Gly-Leu, and Gly-Ile (where Gly denotes glycine), was investigated using a tandem mass spectrometer equipped with an electrospray ionization source and cold ion trap. The ultraviolet photodissociation spectra of the cold gas-phase clusters of Leu and Ile with Na+Trp in the wavelength range of 265–290 nm revealed that the relative intensities of Leu and Ile were only different in the wavelength range of 265–273 nm; however, no differences in the relative intensities were observed when the wavelength exceeded 274 nm. The molecular recognition ability of photoexcited Trp was used for the identification and quantification of Leu and Ile in dipeptides in solution. The mole fractions of Leu and Ile in dipeptides could be determined from the abundances observed in a single product ion spectrum of the cold gas-phase clusters of dipeptides with Na+Trp.
Graphic abstract
中文翻译：
使用光激发色氨酸对肽中的亮氨酸和异亮氨酸残基进行鉴定和定量。
摘要
色氨酸（Trp）对亮氨酸（Leu）和异亮氨酸（Ile）等异构氨基酸以及含异构氨基酸的二肽（Leu-Gly，Ile-Gly，Gly-Leu和Gly）的分子识别能力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-Ile（其中Gly代表甘氨酸）。Na +对亮和冷冷气相团簇的紫外光解离光谱在265-290 nm波长范围内的Trp表明，Leu和Ile的相对强度仅在265-273 nm波长范围内有所不同。但是，当波长超过274nm时，相对强度没有差异。光激发Trp的分子识别能力用于溶液中二肽中Leu和Ile的鉴定和定量。二肽中Leu和Ile的摩尔分数可以通过在具有Na + Trp的二肽冷气相簇的单个产物离子谱中观察到的丰度来确定。
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