Institute of Atomic and Molecular Sciences, Academia Sinica, P. O. Box 23-166, Taipei 10617, Taiwan.
Phys Chem Chem Phys. 2021 Feb 7;23(5):3485-3495. doi: 10.1039/d0cp05868h. Epub 2021 Jan 29.
Collision-induced dissociation (CID) of α-xylose and β-xylose were studied using mass spectrometry and quantum chemistry calculations. Three dissociation channels, namely loss of metal ions, dehydration, and cross-ring dissociation were found. The major dissociation channel of sodium adducts is the loss of sodium ions, and the minor dissociation channels are dehydration and cross-ring dissociation. By contrast, dehydration and cross-ring dissociation are the major dissociation channels of lithium adducts, and the corresponding dissociation mechanisms can be used to determine the anomericity and linkages of xylose in oligosaccharides. These mechanisms include (1) the dehydration branching ratio can be used to differentiate the anomericity of xylose and xylose in oligosaccharides because α-xylose has a larger branching ratio of dehydration than β-xylose, (2) various cross-ring dissociation reactions can be used to identify linkage positions. The oligosaccharide with xylose at the reducing end is predicted to undergo X, X, and A cross-ring dissociation for the 1 → 2, 1 → 3, and 1 → 4 linkages, respectively. Application of these mechanisms to determine the anomericity and linkage positions of xylobiose was demonstrated.
采用质谱和量子化学计算研究了α-木糖和β-木糖的碰撞诱导解离（CID）。发现了三种解离通道，分别是金属离子的损失、脱水和环间解离。钠加合物的主要解离通道是钠离子的损失，次要的解离通道是脱水和环间解离。相比之下，脱水和环间解离是锂加合物的主要解离通道，相应的解离机制可用于确定寡糖中木糖的异头物和键合方式。这些机制包括：（1）脱水分支比可用于区分木糖和寡糖中木糖的异头物，因为α-木糖的脱水分支比β-木糖大；（2）各种环间解离反应可用于鉴定键合位置。预测末端具有木糖的寡糖将分别经历 X、X 和 A 环间解离，用于 1 → 2、1 → 3 和 1 → 4 键。这些机制在确定木二糖的异头物和键合位置中的应用得到了验证。
