The interaction of oxidized FAD radical with dGMP, dAMP and single-stranded DNA (ssDNA) was investigated in neutral aqueous solution using time-resolved 248 nm laser flash photolysis aimed at elucidation of the initia...The interaction of oxidized FAD radical with dGMP, dAMP and single-stranded DNA (ssDNA) was investigated in neutral aqueous solution using time-resolved 248 nm laser flash photolysis aimed at elucidation of the initial photosensitization mechanism. The characterized absorption spectra of transient species were observed. Moreover, direct observation of stabilized DNA guanyl radical has provided transient evidence for site-selective photosensitized damage of DNA at guanine moiety, which has simulated the major initial species produced by the direct effect of ionizing radiation or UV light on DNA.展开更多
Using time-resolved techniques of 337 and 248 nm laser flash photolysis, the photo physical and photochemical processes of riboflavin (RF, vitamin B2) were studied in detail in aqueous solution. The excited triplet st...Using time-resolved techniques of 337 and 248 nm laser flash photolysis, the photo physical and photochemical processes of riboflavin (RF, vitamin B2) were studied in detail in aqueous solution. The excited triplet state of riboflavin (3RF*) was produced with 337 nm laser, while under 248 nm irradiation, both3RF* and hydrated electron (eaq) formed from photoionization could be detected. Photobiological implications have been inferred on the basis of reactivity of3RF* including energy transfer, electron transfer and hydrogen abstraction. The RF·+ was generated by oxidation of SO4 ·-radical with the aim of confirming the results of photolysis.展开更多
Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\...Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\%x\%), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron ( Φ e - ) are determined to be 0.08 and 0.11 for fullerols of C 60 and of C 70 respectively at room temperature (ca. 15℃) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO -· \-4, the fullerol radical cation or neutral radical of C 60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C 70 are observed for the first time.展开更多
Rapid electron transfer from electron adduct and reducing OH adduct of 2-deoxyadenosine-5′-monophosphate acid (dAMP) to riboflavin (RF) and flavin adenine dinucleotide (FAD) was studied using the time-resolved pulse ...Rapid electron transfer from electron adduct and reducing OH adduct of 2-deoxyadenosine-5′-monophosphate acid (dAMP) to riboflavin (RF) and flavin adenine dinucleotide (FAD) was studied using the time-resolved pulse radiolysis techniques. Both spectroscope and kinetic analyses showed that transient absorption spectrum of electron adduct or OH adduct of dAMP formed at first, and men changed to that of radical anion of RF or FAD after several microseconds of pulse. The evidence indicated that electron transfer from electron adduct and reducing OH adduct of dAMP to RF or FAD did occur. From buildup or bleaching kinetics of radical anions of RF and FAD, the rate constants for electron transfer were determined, respectively.展开更多
文摘The interaction of oxidized FAD radical with dGMP, dAMP and single-stranded DNA (ssDNA) was investigated in neutral aqueous solution using time-resolved 248 nm laser flash photolysis aimed at elucidation of the initial photosensitization mechanism. The characterized absorption spectra of transient species were observed. Moreover, direct observation of stabilized DNA guanyl radical has provided transient evidence for site-selective photosensitized damage of DNA at guanine moiety, which has simulated the major initial species produced by the direct effect of ionizing radiation or UV light on DNA.
基金the National Natural Science Foundation of China (Grant No. 39830090).
文摘Using time-resolved techniques of 337 and 248 nm laser flash photolysis, the photo physical and photochemical processes of riboflavin (RF, vitamin B2) were studied in detail in aqueous solution. The excited triplet state of riboflavin (3RF*) was produced with 337 nm laser, while under 248 nm irradiation, both3RF* and hydrated electron (eaq) formed from photoionization could be detected. Photobiological implications have been inferred on the basis of reactivity of3RF* including energy transfer, electron transfer and hydrogen abstraction. The RF·+ was generated by oxidation of SO4 ·-radical with the aim of confirming the results of photolysis.
文摘Fullerols of C 60 and of C 70 \ [C 60 (OH)\-\%n\%, C 70 (OH)\-\%m\%], water\|soluble fullerene derivatives, unlike some other fullerene derivatives (such as C 60 (C\-4H\-6O), C 60 (C\-3H\-7N) and C 60 [C(COOEt)\-2]\-\%x\%), do not result in excited triplet state but in ionization via monophotonic process in aqueous solutions with 248 nm laser. The quantum yields of formation of hydrated electron ( Φ e - ) are determined to be 0.08 and 0.11 for fullerols of C 60 and of C 70 respectively at room temperature (ca. 15℃) with KI solution used as reference. By laser flash photolysis and oxidation of sulfate radical anion SO -· \-4, the fullerol radical cation or neutral radical of C 60 is confirmed to be existent and the transient absorption spectra of fullerol radical cation of C 70 are observed for the first time.
基金Project (No. 39830090) supported by the National Natural Science Foundation of China.
文摘Rapid electron transfer from electron adduct and reducing OH adduct of 2-deoxyadenosine-5′-monophosphate acid (dAMP) to riboflavin (RF) and flavin adenine dinucleotide (FAD) was studied using the time-resolved pulse radiolysis techniques. Both spectroscope and kinetic analyses showed that transient absorption spectrum of electron adduct or OH adduct of dAMP formed at first, and men changed to that of radical anion of RF or FAD after several microseconds of pulse. The evidence indicated that electron transfer from electron adduct and reducing OH adduct of dAMP to RF or FAD did occur. From buildup or bleaching kinetics of radical anions of RF and FAD, the rate constants for electron transfer were determined, respectively.
