Time-resolved resonance Raman, time-resolved UV-visible absorption and DFT calculation study on photo-oxidation of the reduced form of nicotinamide adenine dinucleotide
Time-resolved resonance Raman, time-resolved UV-visible absorption and DFT calculation study on photo-oxidation of the reduced form of nicotinamide adenine dinucleotide
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DOI：
10.1002/jrs.1472
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发表时间：
2006-01-01
影响因子：
2.5
通讯作者：
Takahashi, H
中科院分区：
文献类型：
--
作者：
Takahashi, N;Shinno, T;Takahashi, H
利用纳秒时间分辨共振拉曼和紫外-可见吸收光谱结合密度泛函理论（DFT）/B3 LYP方法研究了还原型烟酰胺腺嘌呤二核苷酸（NADH）在水溶液中的光化学反应.检测到四个瞬变。在370和560 nm处呈现吸收带的瞬态被指定为阳离子自由基NADH（+中心点）。在394 nm处具有吸收带的瞬态被指定为去质子化的中性自由基NAD（中心点）。认为在493 nm处呈现吸收带的瞬态可归因于阴离子自由基NADH（-中心点）。在约700 nm处的宽而强的带被指定为水合电子。实验结果表明，NADH光氧化为NAD（+）的过程是通过NADH（+中心点）和NAD（中心点）逐步进行的。NADH（+中心点）1627 cm（-1）处的拉曼谱带归属于二氢烟酰胺部分质子化吡啶环的C=C对称伸展。结果表明，质子化吡啶环的C=C对称伸缩在从基态到NADH（+中心点）的过程中表现出从1688 cm（-1）到1627 cm（-1）的低波数位移。这意味着质子化的吡啶环在电离时被大大削弱，与DFT计算的结果雅阁。版权所有（C）2006约翰威利父子有限公司
Photochemical reaction of the reduced form of nicotinamide adenine dinucleotide (NADH) was studied in aqueous solutions using nanosecond time-resolved resonance Raman and UV-visible absorption spectroscopies combined with DFT/B3LYP calculations. Four transients were detected. A transient exhibiting absorption bands at 370 and 560 nm was assigned to the cation radical NADH(+center dot). A transient having an absorption band at 394 nm was assigned to the deprotonated neutral radical NAD(center dot). A transient exhibiting an absorption band at 493 nm was considered to be attributable to the anion radical NADH(-center dot). The broad and strong band at about 700 nm was assigned to hydrated electrons. It was concluded that the photo-oxidation of NADH to NAD(+) proceeded stepwise via NADH(+center dot) and NAD(center dot). The Raman band at 1627 cm(-1) of NADH(+center dot) was assigned to the C=C symmetric stretch of the protonated pyridyl ring of the dihydronicotinamide moiety. It was shown that the C=C symmetric stretch of the protonated pyridyl ring exhibited a low-wavenumber shift from 1688 cm(-1) to 1627 cm(-1) on going from the ground state to NADH(+center dot). This implies that the protonated pyridyl ring is weakened considerably on ionization in good accord with the DFT calculations. Copyright (C) 2006 John Wiley & Sons, Ltd.