It is well-known that nucleoside-derived radicals play crucial roles in cellular activity.However,due to the instability of the radicals and their widespread isomerization,experimental research on their generation and...It is well-known that nucleoside-derived radicals play crucial roles in cellular activity.However,due to the instability of the radicals and their widespread isomerization,experimental research on their generation and structural characterization has been a challenge for a long time.Herein,we provide a unique approach to selectively generate the isomers of nucleoside radicals in the gas phase.Through the process of ultraviolet photodissociation(UVPD)at 285 and 245 nm,we were able to selectively produce O_(2) and C5 isomers of cytidine radicals from a single precursor ion of protonated 5-I-cytidine.These radical isomers were structurally characterized by a combination of infrared multiphoton dissociation(IRMPD)spectroscopy of the mass-selected ions and systematic computations.The structural characteristics of cytidine radical isomers such as the anti/syn glycosidic link and the North/South sugar ring conformation were disclosed.The key to selectivity lay in whether the excess energy of the precursor ions after absorbing one ultraviolet photon and undergoing the homo-cleavage of the C–I bond could overcome the corresponding energy barrier of the isomerization.This method provides an effective way for the selective generation of radical isomers with rich flexibility by wavelength-regulated UVPD and reasonable introductions of C–I bonds in the precursors.展开更多
基金supported financially by the National Natural Science Foundation of China(NSFCgrant nos.22174076 and 21627801).
文摘It is well-known that nucleoside-derived radicals play crucial roles in cellular activity.However,due to the instability of the radicals and their widespread isomerization,experimental research on their generation and structural characterization has been a challenge for a long time.Herein,we provide a unique approach to selectively generate the isomers of nucleoside radicals in the gas phase.Through the process of ultraviolet photodissociation(UVPD)at 285 and 245 nm,we were able to selectively produce O_(2) and C5 isomers of cytidine radicals from a single precursor ion of protonated 5-I-cytidine.These radical isomers were structurally characterized by a combination of infrared multiphoton dissociation(IRMPD)spectroscopy of the mass-selected ions and systematic computations.The structural characteristics of cytidine radical isomers such as the anti/syn glycosidic link and the North/South sugar ring conformation were disclosed.The key to selectivity lay in whether the excess energy of the precursor ions after absorbing one ultraviolet photon and undergoing the homo-cleavage of the C–I bond could overcome the corresponding energy barrier of the isomerization.This method provides an effective way for the selective generation of radical isomers with rich flexibility by wavelength-regulated UVPD and reasonable introductions of C–I bonds in the precursors.
