Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the...Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor, this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry（ DESI-MS）, without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer（ m/z 841 ） is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range（pH = 1-5 ）, and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.展开更多
Threonine-substituted serine octamer ions were generated by electrospray ionization（ESI） and investigated by mass spectrometry and infrared photodissociation（IRPD） spectroscopy. IRPD spectra of[L-Ser_7＋ L/D-Thr_1...Threonine-substituted serine octamer ions were generated by electrospray ionization（ESI） and investigated by mass spectrometry and infrared photodissociation（IRPD） spectroscopy. IRPD spectra of[L-Ser_7＋ L/D-Thr_1]H~＋and [L-Ser_6＋ L/D-Thr_2]H~＋were obtained in the range of 2700–3600 cm^（-1）. Chiral differentiation was achieved by comparing their IRPD spectra. The main difference located in the range of 3300–3500 cm^（-1）. And the results indicate the substitution of L-Ser by D-Thr could weaken the intermolecular H-bonds and loosen the original structures of serine octamers.展开更多
基金Supported by the National Natural Science Foundation of China(No.20505003).
文摘Serine, one of the nonessential amino acids, is of principal interest because of its capability to form magic-number ionic clusters, which provide a remarkable preference for homochirality. With L-aspartic acid as the precursor, this study provides experimental evidence for serine formation in weak acidified aqueous solutions in the presence of iron, with exposure to sunlight, which simulates the natural conditions of the prebiotic aqueous environment. The resultant mixture is directly analyzed via desorption electrospray ionization mass spectrometry（ DESI-MS）, without any sample preseparation. The serine monomer is successfully detected as protonated molecules, giving a peak at m/z 106, which is confirmed by the MS/MS fragments. Protonated serine octamer（ m/z 841 ） is also observed with significant abundance in the MS spectra and is confirmed by the MS/MS data, which shows the formation of the serine octamer by a synthesized serine in the resultant mixture. It is also found that the serine octamer yielded equivalent abundance in the DESI mass spectra in a wide pH range（pH = 1-5 ）, and that existence of ferrous salt and sunshine are essential for the conversion of aspartic acid to serine in the acidic water solution.
基金Financial support from the National Natural Science Foundation of China(No.21475065)
文摘Threonine-substituted serine octamer ions were generated by electrospray ionization（ESI） and investigated by mass spectrometry and infrared photodissociation（IRPD） spectroscopy. IRPD spectra of[L-Ser_7＋ L/D-Thr_1]H~＋and [L-Ser_6＋ L/D-Thr_2]H~＋were obtained in the range of 2700–3600 cm^（-1）. Chiral differentiation was achieved by comparing their IRPD spectra. The main difference located in the range of 3300–3500 cm^（-1）. And the results indicate the substitution of L-Ser by D-Thr could weaken the intermolecular H-bonds and loosen the original structures of serine octamers.
