水液相环境下羟自由基诱导的苯丙氨酸分子损伤机理

Mechanism of phenylalanine damage induced by hydroxyl radicals in water-liquid phase environment

在MP2/SMD/6-311++g(3df, 2pd)//WB97X-D/SMD/6-311++G(d, p)理论水平上,研究了水液相环境下羟自由基诱导的苯丙氨酸分子的损伤机理。研究发现,羟自由基(水分子簇)抽取α-氢、β-氢、苯环-氢以及羟自由基与苯环加成均可致苯丙氨酸分子损伤。势能面计算表明,羟自由基(水分子簇)抽取α-氢和β-氢的最低能垒分别为68.4和89.3 kJ·mol^-1,羟自由基抽取苯环-氢的最低能垒为111.6 kJ·mol^-1,羟自由基加成到苯环不同位点碳的能垒大约在106.5~110.2 kJ·mol^-1,羟自由基(水分子簇)抽α-氢和β-氢是显著的放热反应。结果表明,羟自由基(水分子簇)抽取α-氢是苯丙氨酸分子损伤的主要途径。

The concerned reaction was researched at the MP2/SMD/6-311++g(3 df, 2 pd)//WB97 X-D/SMD/6-311++G(d, p) level of theory. Our study shows that α-H, β-H and benzene ring-H abstraction of hydroxyl radicals(water clusters) can induce the phenylalanine damage, as well as the addition of hydroxyl radicals to benzene ring. The calculation of potential energy surface shows that the lowest energy barrier for α-H and β-H abstraction of hydroxyl radicals(water clusters) is 68.4 and 89.3 kJ·mol^-1 respectively, The lowest energy barrier for benzene ring-H abstraction of hydroxyl radicals(water clusters) is 111.6 kJ·mol^-1, and the energy barrier for the addition of hydroxyl radicals to different sites of benzene ring is about 106.5 to 110.2 kJ·mol^-1. The α-H and β-H abstraction of hydroxyl radicals(water clusters) is a significant exothermic reaction. These results showed that α-H abstraction of hydroxyl radicals(water clusters) is the main pathway of phenylalanine damage.