A novel mechanism for cleavage of three typical α(1 → 2), α(1 → 4) and β(1 → 4) glucosidic bonds induced by hydroxyl free radical was examined with DFT theory at B3LYP/6–31 + G(d,p) level using PCM water solvent model. It was found that the hydrogen abstraction from the CH bonds outside the saccharide rings could induce the hydrogen transfer from the hydroxyl at the radical carbon to the oxygen atom of saccharide ring with the mediation of water, which led to the opening of saccharide ring and the breakage of glucosidic bonds. Alternatively, the hydrogen in COH outside the saccharide ring of maltose and sucrose could also transfer to the adjacent glucosidic oxygen atom with a water molecule mediation to make glucosidic bond break directly. Based on this study, it can be well explained the experimental results that the oxidation of some oligosaccharides with hydroxyl free radicals can produce molecules of glucose, fructose and other monosaccharides.

中文翻译：

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羟基自由基诱导的三个典型糖苷键的裂解机理

用DFT理论在B3LYP / 6–31 + G（d）下研究了由羟基自由基诱导的三个典型的α（1→2），α（1→4）和β（1→4）糖苷键裂解的新机理。 ，p）水平使用PCM水溶剂模型。发现从C中提取氢在水的介导下，糖环外的H键可引起氢从自由基碳原子上的羟基转移到糖环的氧原子上，从而导致糖环的开环和糖苷键的断裂。或者，氢在C麦芽糖和蔗糖的糖环外的OH也可以在水分子的介导下转移到相邻的糖苷氧原子上，从而使糖苷键直接断裂。基于这项研究，可以很好地解释实验结果，即某些寡糖被羟基自由基氧化可以产生葡萄糖，果糖和其他单糖分子。