CAJ | 학술논문

为了探索金属离子对含有不同侧链的多肽气相解离的影响,采用质谱法研究了碱金属离子Li+, Na+, K+, Rb+和Cs+分别与丝氨酸、亮氨酸和赖氨酸五肽(分别简写为S5, L5和K5)形成的复合物的裂解反应.质谱定性结果表明,5种碱金属离子均可以在气相中与丝氨酸、亮氨酸和赖氨酸五肽形成配合比为1：1和2：1的非共价复合物；竞争反应结果表明,随着碱金属离子半径的增加,它们与3种五肽的结合能力逐渐减弱.质谱定量结果表明, K+与丝氨酸、亮氨酸和赖氨酸五肽复合物的结合常数分别为8.94×104,2.83×104和2.50×103 L/mol,表明K+与五肽复合物的结合强度按照丝氨酸、亮氨酸和赖氨酸的顺序依次减小.含不同侧链碱金属离子-五肽复合物的碰撞诱导解离结果表明,复合物的碎裂主要发生在骨架上,丝氨酸五肽复合物最易碎裂,亮氨酸五肽复合物其次,赖氨酸五肽复合物则较难碎裂,且3种复合物的侧链断裂情况也呈现明显差异.此外,研究了Na+与亮氨酸五肽复合物所产生的碎片离子,分析了不同离子之间的来源关系,并以Dunbar的复合物理论模型为依据,推测在碎裂过程中,碱金属离子可能向五肽的碳端或氮端偏移.质谱碎片分析结果表明,在2：1的非共价复合物中,第一个碱金属离子与五肽上4个酰胺键的羰基结合,第二个碱金属离子与五肽的羧基氧原子结合.
위료탐색금속리자대함유불동측련적다태기상해리적영향,채용질보법연구료감금속리자Li+, Na+, K+, Rb+화Cs+분별여사안산、량안산화뢰안산오태(분별간사위S5, L5화K5)형성적복합물적렬해반응.질보정성결과표명,5충감금속리자균가이재기상중여사안산、량안산화뢰안산오태형성배합비위1：1화2：1적비공개복합물；경쟁반응결과표명,수착감금속리자반경적증가,타문여3충오태적결합능력축점감약.질보정량결과표명, K+여사안산、량안산화뢰안산오태복합물적결합상수분별위8.94×104,2.83×104화2.50×103 L/mol,표명K+여오태복합물적결합강도안조사안산、량안산화뢰안산적순서의차감소.함불동측련감금속리자-오태복합물적팽당유도해리결과표명,복합물적쇄렬주요발생재골가상,사안산오태복합물최역쇄렬,량안산오태복합물기차,뢰안산오태복합물칙교난쇄렬,차3충복합물적측련단렬정황야정현명현차이.차외,연구료Na+여량안산오태복합물소산생적쇄편리자,분석료불동리자지간적래원관계,병이Dunbar적복합물이론모형위의거,추측재쇄렬과정중,감금속리자가능향오태적탄단혹담단편이.질보쇄편분석결과표명,재2：1적비공개복합물중,제일개감금속리자여오태상4개선알건적탄기결합,제이개감금속리자여오태적최기양원자결합.
For exploring the effects of alkali metal ions on the dissociations of peptides with different side chains in the gas phase, the complexes of Li+, Na+, K+, Rb+ and Cs+ with pentapeptides, Ser-Ser-Ser-Ser-Ser( S5 ) , Leu-Leu-Leu-Leu-Leu ( L5 ) and Lys-Lys-Lys-Lys-Lys ( K5 ) , were chosen to investigate the frag-mentation reaction pathways by mass spectrometry. The experimental results indicated that alkali metal ions and S5, L5, K5 can form 1:1 and 2:1 non-covalent complexes in the gas phase, and the binding strength between alkali metal ions and pentapeptides descend with the increasing of the radii of alkali metal ions. Quantitative analyses of mass spectra demonstrated that the binding constants for the complexes of K+with S5 , L5 and K5 are 8.94í104 , 2.83í104 and 2.50í103 L/mol, respectively, revealing that the binding strength of complexes decrease in order of S5 , L5 and K5 . The analyses of the fragment ions arising from the complexes of alkali metal ions with pentapeptides showed that the dissociations mainly occur in the backbones of the pep-tides. Among three pentapeptides, the complexes of pentaserines are the easiest to fragment, pentaleucines take second place, while pentalysines are the hardest. The dissociations also occur in the side chains, and there are significant differences among the three complexes. Moreover, the relationships among various frag-ment ions arising from the complex of Na+ with L5 were tested. Based on the theoretical model of Dunbar, it was proposed that in the fragmentation process, the alkali metal ion may shift to the N- or C-terminal of the pentapeptide. In 2:1 complex, the first alkali metal ion may conjugate to the carbonyl groups of four amides, while the second one may conjugate to the oxygen atoms of carboxyl group of the pentapeptide.