本文選題：串聯(lián)質譜 + 多肽碎裂��； 參考：《吉林大學》2017年碩士論文

【摘要】：Na離子作為常見的電荷載體,在電噴霧質譜分析中極易被檢測,對多肽的碎裂有明顯的影響。與經典的質子化肽的“移動質子”模型相比,Na離子加和肽的碎裂更傾向于電荷遠程控制作用。本文通過碰撞誘導解離(collision induced dissociation,CID)碎裂實驗和量子化學計算研究了特定氨基酸組成的多肽在H+加和與Na~+加和下的碎裂差異,目的是探究Na~+在電荷遠程控制作用的過程中對多肽的氣相結構和反應路徑的影響。本文實驗共分為三個部分:(1)谷氨酰胺作為天然易變的氨基酸,在多種生命活動中扮演著重要的角色。通過對C端為谷氨酰胺的多肽進行質譜的碎裂研究,我們首次觀察和驗證了谷氨酰胺殘基丟失NH3產生戊二酸酐結構的bn*離子及其進一步丟失CO的現象。與質子化的碎裂對比,發(fā)現位于多肽C端的谷氨酰胺在鈉加和下更具有活性,更易被多肽的C端-COOH親核進攻丟失NH3和發(fā)生進一步的碎裂。通過量子化學計算,解釋了H+加和與Na~+加和下的碎裂差異。(2)研究了不含酸堿性殘基的非極性肽LAXA(X=Gly,Ala,Val,Leu,Ile和Phe)的碎裂,以對比H+加和與Na~+加和下的差異。當與H+結合時,串聯(lián)質譜圖中y2/b2的離子峰強比與Xxx殘基有關。量子化學計算結果表明,多肽的質子親和力與殘基Xxx結構成線性關系。當有Na~+參與時,Xxx殘基N端的酰胺鍵更易發(fā)生斷裂,產生了少見的[H-Xxx-OH+Na]+。通過量子化學計算,探究了[H-Xxx-OH+Na]+中的金屬-π相互作用。(3)研究了N端為Lys的多肽在碰撞誘導解離模式下的碎裂。考慮到N端的Lys殘基由于較強的質子親和力可結合質子,而堿金屬可作為離子化C端的配體,本文研究了[M+H+Cat]2+的碎裂,觀察到了單質子化下不易檢測到的yn離子,并結合量子化學計算解釋了不同堿金屬陽離子(Li,Na,K)對碎裂行為的影響。
[Abstract]:As a common charge carrier, Na ion is easy to be detected in electrospray mass spectrometry (ESI) and has an obvious effect on the fragmentation of polypeptides. Compared with the "moving proton" model of the classical protonated peptide, the addition of Na + and the fragmentation of the peptide are more inclined to charge remote control. In this paper, the fragmentation differences of polypeptides with specific amino acid composition under the sum of H and Na ~ + have been studied by collision-induced dissociation induced splitting experiments and quantum chemical calculations. The aim of this study was to investigate the effect of Na ~ ~ on the gas phase structure and reaction pathway of polypeptides during the process of charge remote control. The experiment consists of three parts: 1) glutamine, as a natural variable amino acid, plays an important role in many life activities. Based on the fragmentation of C-terminal glutamine peptides, we observed and verified for the first time the production of glutaric anhydride ion by NH3 and the further loss of CO. Compared with the protonation fragmentation, it was found that the glutamine at the C-terminal of the polypeptide was more active under the addition of sodium, and was more susceptible to the loss of NH3 and further fragmentation by the nucleophilic attack of the C-COOH terminal of the peptide. By means of quantum chemistry calculation, the fragmentation difference between H + and Na ~ + is explained. The fragmentation of nonpolar peptides LAXAZOXYL ALAA ALALYL VALALEL and PHE without acid and alkaline residues are studied in order to compare the difference between H + sum and Na ~ + addition under Ile and Phe. the results are as follows: (1) the difference between H + and Na ~ + addition is compared with that of Na- + in the presence of H + and Na ~ +. When combined with H, the ratio of ion peak strength of y2/b2 in tandem mass spectrometry is related to the Xxx residue. The results of quantum chemistry show that the proton affinity of polypeptide is linear with the Xxx structure of residue. When Na ~ + is involved, the N-terminal amide bond of the xxx residue is more prone to fracture, resulting in the rare [H-Xxx-OH Na]. In this paper, the metal-蟺 interaction in [H-Xxx-OH Na] is investigated by quantum chemical calculation. The fragmentation of N-terminal polypeptides with Lys in collision-induced dissociation mode is investigated. Considering that the N-terminal Lys residue can bind to protons because of its strong proton affinity, and that alkali metals can be used as ligands for ionization of C-terminal, the fragmentation of [M H Cat] _ 2 has been studied, and the yn ions which are difficult to detect under single protonation have been observed. The effects of different alkaline-metal cations on the fragmentation behavior were explained by quantum chemical calculations.
【學位授予單位】：吉林大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：O629.72;O657.63

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