羟甲基取代效应对甘氨酸质子化的作用  

Hydroxymethyl effect on the proton transfer mechanism of glycine

作　　者：吴文胜[1] 孟祥军[2] 李志伟[1] 

机构地区：[1]肇庆学院化学化工学院,广东肇庆526061 [2]唐山师范学院化学系,河北唐山063000

出　　处：《化学试剂》2011年第8期693-696,762,共5页Chemical Reagents

基　　金：广东省自然科学基金资助项目(1045260610-1004869);河北省教育厅科学研究基金资助项目(22007205);肇庆学院自然科学基金资助项目(0933)

摘　　要：采用MP2/6-31++G**//B3LYP/6-31++G**方法研究了丝氨酸和甘氨酸水致质子迁移的相对难易,探讨了羟甲基取代效应。得到两个主要结论:1)羟甲基取代甘氨酸中的α-H后,其吸电子效应削弱了迁移质子所在的化学键,导致质子迁移所需的最少水分子数目由2个减少为1个;2)通过比较羟甲基取代前后的质子迁移过程,发现羟甲基效应使反应势垒降低了0.917 kJ/mol,使反应吸热减少了6.766 kJ/mol。The proton transfer in hydrated fl-hydroxyalanine and glycine was studied to probe into the substitution effect of hydroxymethyl by MP2/6-31 ^＊＊ G ^＊＊//β3LYP/6-31^＊＊＋ G ^＊＊method. Two conclusions were drawn as below, 1 ） the chemical bond containing the α-H has been weakened by hydroxymethyl effection, resulting in the decreasing of the minimum number of water molecular necessary to cause proton transfer from 2 to 1 ;2 ） the reaction potential barrier and the reaction endotherm of the proton transfer were reduced by 0. 917 and 6. 766 kJ/mol,respectively,after the α-H of glyeine being replaced by hydroxymethyl.

关 键 词：取代基效应 丝氨酸 甘氨酸 质子迁移 量子化学 

分 类 号：O641[理学—物理化学]