Site specific sequestering and stabilization of charge in peptides by supramolecular adduct formation with 18-crown-6 ether by way of electrospray ionization
Site specific sequestering and stabilization of charge in peptides by supramolecular adduct formation with 18-crown-6 ether by way of electrospray ionization
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DOI：
10.1016/s1387-3806(01)00431-6
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发表时间：
2001-10-01
影响因子：
1.8
通讯作者：
Beauchamp, JL
中科院分区：
文献类型：
--
作者：
Julian, RR;Beauchamp, JL
用电喷雾四极杆离子阱质谱研究了18-冠-6-醚（18 C6）与生物相关基团的结合。分离的赖氨酸是一种特殊情况，其中18 C6连接到N-末端，从所得的盐桥结构获得稳定性。在肽中，18 C6通过与侧链上的伯质子化胺的特定氢键与赖氨酸形成稳定的超分子加合物。18 C6将与相邻的赖氨酸结合，形成多电荷复合物。例如，在18 C6和四赖氨酸的混合物的光谱中，最强的峰是连接有四个冠醚的四重电荷肽。竞争性结合18 C6的其他碱性位点，如N-末端，组氨酸，精氨酸限制了这种技术的实用性的分子识别赖氨酸。18 C6与蛋白质如细胞色素-C（CytC）和牛胰蛋白酶抑制剂（BPTI）的加合物揭示了与潜在结合位点的可及性相关的结构信息。与18 C6形成加合物似乎增加了带电液滴中肽的表面活性，并在ESI过程中的离子去溶剂化期间抑制去质子化。这些效应增加了分析物的主要电荷状态和离子丰度。由18 C6提供的电荷的螯合和稳定允许检测通常难以使用ESI观察的物质，例如甘氨酸。讨论了18 C6加合物的观测行为与ESI离子蒸发机理之间的关系。(C)2001 Elsevier Science B.V.
The binding of 18-crown-6-ether (18C6) to biologically relevant groups is studied by way of electrospray ionization (ESI) quadrupole ion-trap mass spectrometry. Isolated lysine is a special case in which the 18C6 attaches to the N-terminus, deriving stability from the resulting salt-bridge structure, In a peptide, 18C6 forms a stable supramolecular adduct with lysine by way of specific hydrogen bonding with the primary protonated amine on the side chain. 18C6 will bind to adjacent lysines, forming multiply charged complexes. For example, the most intense peak in the spectrum of a mixture of 18C6 and tetralysine is the quadruply charged peptide with four crown ethers attached. Competitive binding of 18C6 by other basic sites such as the n-terminus, histidine, and arginine limits the utility of this technique for the molecular recognition of lysine. Adducts of 18C6 with proteins such as cytochrome-c (CytC) and bovine pancreatic trypsin inhibitor (BPTI) reveal structural information relevant to the accessibility of potential binding sites. Adduct formation with 18C6 appears to increase the surface activity of peptides in a charged droplet and inhibits deprotonation during ion desolvation in the ESI process. These effects increase both the primary charge state and ion abundance of the analyte. Sequestering and stabilization of charge provided by 18C6 allows for the detection of species that are normally difficult to observe using ESI, such as glycine. The relationship between the observed behaviors of 18C6 adducts and the proposed ion evaporation mechanism of ESI is discussed. (C) 2001 Elsevier Science B.V.