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Collision-induced dissociation of sodiated glucose, galactose, and mannose, and the identification of anomeric configurations†
Physical Chemistry Chemical Physics ( IF 3.3 ) Pub Date : 2018-07-07 00:00:00 , DOI: 10.1039/c8cp03753a
Hai Thi Huynh,Huu Trong Phan,Po-Jen Hsu,Jien-Lian Chen,Hock Seng Nguan,Shang-Ting Tsai,Thantip Roongcharoen,Chia Yen Liew,Chi-Kung Ni,Jer-Lai Kuo

Collision-induced dissociation of sodiated α-glucose, β-glucose, α-galactose, β-galactose, α-mannose, and β-mannose was studied using electronic structure calculations and resonance excitation in a low-pressure linear ion trap. We made an extensive search of conformers and transition states in calculations to ensure the transition state with the lowest barrier height for each dissociation channel could be located. The major dissociation channels, in addition to desodiation, are cross-ring dissociation and dehydration. Cross-ring dissociation starts with H atom transfer from the O1 atom to the O0 atom, followed by the cleavage of the C1–O0 bond. Dehydration of the anomer with O1 and O2 atoms in the cis configuration involves the transfer of an H atom from the O2 atom to the O1 atom, followed by the cleavage of the C1–O1 bond. In contrast, dehydration of the anomer with O1 and O2 atoms in the trans configuration mainly occurs through H atom transfer from the O3 or O2 atom to the O1 atom for glucose, from the O3 or O4 atom to the O1 atom for galactose, and from the O4 or O2 atom to the O1 atom for mannose, followed by the cleavage of the C1–O1 bond. The dehydration barrier heights are lower than those of cross-ring dissociation for cis anomers, but higher than those of cross-ring dissociation for trans anomers. The relative barrier heights from calculations are consistent with the experimental measurements of branching ratios. Both computational and experimental results show that the branching ratio of dehydration can be generalized as a simple rule for rapidly identifying the anomeric configurations of these monosaccharides.

中文翻译:

碰撞诱导的葡萄糖,半乳糖和甘露糖的解离,以及端基异构构型的识别

使用电子结构计算和在低压线性离子阱中的共振激发,研究了碰撞诱导的α-葡萄糖,β-葡萄糖,α-半乳糖,β-半乳糖,α-甘露糖和β-甘露糖的解离。我们对计算中的构象异构体和过渡态进行了广泛的搜索,以确保可以找到每个解离通道的最低势垒高度的过渡态。除沉降以外,主要的离解通道是环环离解和脱水。交叉环解离以H原子从O1原子转移到O0原子开始,然后裂解C1-O0键。顺式中的O1和O2原子使异头物脱水构型涉及一个H原子从O2原子转移到O1原子,然后裂解C1-O1键。相反,反式构型中带有O1和O2原子的异构体脱水主要是通过H原子从O3或O2原子转移到葡萄糖的O1原子,从O3或O4原子转移到半乳糖的O1原子,以及将O4或O2原子转换为O1原子的甘露糖,然后裂解C1-O1键。脱水势垒高度比那些用于跨环解离的低顺式端基异构体比跨环解离的对,但较高的反式异头物。计算得出的相对势垒高度与支化比的实验测量值一致。计算结果和实验结果均表明,可以将脱水的支化率概括为快速识别这些单糖的异头构型的简单规则。
更新日期:2018-07-07
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