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Resonance Raman investigation of dithionite‐reduced cobalamin
Journal of Raman Spectroscopy ( IF 2.4 ) Pub Date : 2020-05-29 , DOI: 10.1002/jrs.5909 Kaoru Mieda‐Higa 1 , Abdullah Al Mamun 2 , Takashi Ogura 1 , Teizo Kitagawa 1 , Pawel M. Kozlowski 2
Journal of Raman Spectroscopy ( IF 2.4 ) Pub Date : 2020-05-29 , DOI: 10.1002/jrs.5909 Kaoru Mieda‐Higa 1 , Abdullah Al Mamun 2 , Takashi Ogura 1 , Teizo Kitagawa 1 , Pawel M. Kozlowski 2
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Absorption (Abs) and resonance Raman (rR) spectroscopy along with density functional theory (DFT) have been applied to investigate the derivatives of vitamin B12 (or cobalamins = Cbls). Cbls are cobalt‐containing corrin complexes, vibrations of which can be probed using rR spectroscopy. The oxidation state of Co ion in Cbls can range between Co3+, Co2+, and Co1+, and axially, cobalt can be coordinated by variety of ligands. Recent spectroscopic study revealed that Co2+Cbl reduced by dithionite (DTH) exhibited a unique property distinct from other Co2+Cbls. Accordingly, in this study, rR spectra of Co2+Cbls reduced by DTH were compared with these reduced by dithiothreitol (DTT). The DTT‐reduced Cbl gave ordinary rR spectrum at pH 3 and 8. On the other hand, the DTH‐reduced Cbl gave different rR spectra at pH 3 and 8 and contained a new rR band at 987 cm−1, which is absent with the DTT‐reduced one. The α and γ Abs bands of DTH‐reduced Cbls were also shifted to shorter wavelengths and exhibited broadening. To understand these rR spectra, geometry optimization and frequency calculations using DFT have been carried out for different structural models of Cbls and compared with experiment. Based on current spectroscopic studies and computation, we deduced that the DTH‐reduced Cbl has SO2‐. radical anion at an axial coordination position of Co2+ and that the ππ* transition of corrin ring is partially mixed with π bond of SO2‐. radical anion, giving rise to the S=O stretching rR band in resonance with the γ Abs band.
中文翻译：
连二亚硫酸盐还原钴胺素的共振拉曼研究
吸收（Abs）和共振拉曼（rR）光谱以及密度泛函理论（DFT）已用于研究维生素B 12的衍生物（或钴胺素= Cbls）。Cbls是含钴的柯林配合物，可以使用rR光谱探测其振动。Cbls中Co离子的氧化态可介于Co 3+，Co 2+和Co 1+之间，并且在轴向上，钴可通过各种配体进行配位。最近的光谱研究表明，连二亚硫酸盐（DTH）还原的Co 2+ Cbl表现出不同于其他Co 2+ Cbls的独特性能。因此，在这项研究中，Co 2+的rR光谱将通过DTH还原的Cbl与通过二硫苏糖醇（DTT）还原的Cbl进行比较。的DTT还原的Cbl给普通RR光谱在pH 3和8.在另一方面，DTH减小边界层，得到不同光谱RR在pH 3和8，并在987厘米包含一个新的RR带-1，这是不存在与DTT减少的一种。降低DTH的Cbls的α和γAbs谱带也移至较短的波长并表现出加宽。为了理解这些rR谱，已经针对不同的Cbls结构模型进行了DFT的几何优化和频率计算，并与实验进行了比较。根据目前的光谱研究和计算，我们推论出DTH还原后的Cbl具有SO 2- 。Co 2+轴向配位上的自由基阴离子Corrin环的ππ*跃迁与SO 2-的π键部分混合。自由基阴离子，与γAbs带共振产生S = O拉伸rR带。
更新日期：2020-05-29
中文翻译：
连二亚硫酸盐还原钴胺素的共振拉曼研究
吸收（Abs）和共振拉曼（rR）光谱以及密度泛函理论（DFT）已用于研究维生素B 12的衍生物（或钴胺素= Cbls）。Cbls是含钴的柯林配合物，可以使用rR光谱探测其振动。Cbls中Co离子的氧化态可介于Co 3+，Co 2+和Co 1+之间，并且在轴向上，钴可通过各种配体进行配位。最近的光谱研究表明，连二亚硫酸盐（DTH）还原的Co 2+ Cbl表现出不同于其他Co 2+ Cbls的独特性能。因此，在这项研究中，Co 2+的rR光谱将通过DTH还原的Cbl与通过二硫苏糖醇（DTT）还原的Cbl进行比较。的DTT还原的Cbl给普通RR光谱在pH 3和8.在另一方面，DTH减小边界层，得到不同光谱RR在pH 3和8，并在987厘米包含一个新的RR带-1，这是不存在与DTT减少的一种。降低DTH的Cbls的α和γAbs谱带也移至较短的波长并表现出加宽。为了理解这些rR谱，已经针对不同的Cbls结构模型进行了DFT的几何优化和频率计算，并与实验进行了比较。根据目前的光谱研究和计算，我们推论出DTH还原后的Cbl具有SO 2- 。Co 2+轴向配位上的自由基阴离子Corrin环的ππ*跃迁与SO 2-的π键部分混合。自由基阴离子，与γAbs带共振产生S = O拉伸rR带。
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