亮氨酸-脑啡肽结合H^+和Li^+的氢氘交换实验与理论研究  

Investigation of Protonated and Lithiated Leucine-Enkephalin by Hydrogen/Deuterium Exchange and Theoretical Calculations

作　　者：陈银娟 熊行创[3] 李振华[2] 江游[3] 方向[3] 戴新华[3] 丁传凡[2] CHEN Yin-Juan;XIONG Xing-Chuang;LI Zhen-Hua;JIANG You;FANG Xiang;DAI Xin-Hua;DING Chuan-Fan(School of Chemical Science and Engineering,Tongji University,Shanghai 200092,China;Department of Chemistry,Fudan University,Shanghai 200433,China;Chemical Metrology&Analytical Science Division,National Institute of Metrology,Beijing 100013,China)

机构地区：[1]同济大学化学科学与工程学院,上海200092 [2]复旦大学化学系,上海200433 [3]中国计量科学研究院化学计量与分析科学研究所,北京100013

出　　处：《分析化学》2018年第4期556-562,共7页Chinese Journal of Analytical Chemistry

基　　金：国家自然科学基金项目(Nos.21773035;21605135);国家重大仪器设备开发专项(No.2012YQ22011307)资助~~

摘　　要：气相氢氘交换质谱(HDX-MS)实验与量子化学计算结合,比较了亮氨酸-脑啡肽(YGGFL)结合H^+和Li^+的反应和结构差异性。HDX-MS结果表明,在相同的实验条件下,[YGGFL+Li]^+在交换5个氢原子后,氢氘同位素反应趋于停止,而[YGGFL+H]^+上的9个可交换氢原子均可发生交换。这表明Li^+会降低脑啡肽的氢氘交换率。理论计算发现,两种离子具有不同的最稳定结构:Li^+与脑啡肽肽上的4个羰基氧原子结合能量最低,而脑啡肽氨基端发生质子化后产生最稳定的[YGGFL+H]^+。基于此稳定结构,实验进一步从离子结构差异性和质子亲和势等方面对HDX实验结果进行了分析。Differences of protonated and lithiated leucine-enkephalin(LE)were investigated by hydrogen deuterium exchange-mass spectrometry(HDX-MS)combined with quantum chemistry calculation.The results revealed that the protonated ions possessed very high product yield with all hydrogen atoms being exchanged,while the reaction of lithiated LE stopped after exchanging five hydrogen atoms in the same experimental conditions.The different HDX behaviours probably indicated their conformational differences.To further clarify the experimental results,the most stable conformations of protonated and lithiated leucine-enkephalin were calculated by density functional theory.It was found that terminal amino group was the most thermodynamically stable protonation site,while Li+in coordination of four carbonyl oxygen atoms formed the most favourable lithiated LE.The reaction field reduction of lithium LE was probably due to the less acidity of hydrogen atoms and the increasing rigid conformation change induced by lithium ion.

关 键 词：氢氘交换 亮氨酸-脑啡肽 质谱 锂离子 气相结构 

分 类 号：O629.72[理学—有机化学] O657.63[理学—化学]