Structures and stabilities of small gas-phase ions

这个项目涉及肽的基础化学。肽是由氨基酸组成的小分子，氨基酸是蛋白质的构建单元。 氨基酸的组合方式决定了蛋白质的结构及其生物学功能。 我们用一种酶将蛋白质分解成肽来确定氨基酸的序列。 我研究质子化肽的结构以及它们如何在质谱仪中分解。氨基酸残基通常从质子化肽的一端丢失。这使得有可能从形成的片段中鉴定肽（以及由此衍生的蛋白质）。 当线性中间体离子通过环状离子重新排列，然后重新打开不同的线性离子时，就会出现问题。这导致不正确的序列信息。 在这个建议中，我将检查不寻常的离子的结构形成的质子化肽片段使用质谱，分子建模和红外光谱的组合。理论将提供这些离子碎片和/或重新排列的机制的见解。

This project involves fundamental chemistry of peptides. Peptides are small molecules composed of amino acids, the building blocks of proteins. How amino acids are combined defines the structure of a protein and its biological function. We determine the sequence of amino acids using an enzyme to break the protein into peptides. I study the structures of protonated peptides and how they break apart in a mass spectrometer. Amino acid residues are usually lost from one end of a protonated peptide. This makes it possible to identify a peptide (and hence the protein from which it was derived) from the fragments formed. Problems arise when linear intermediate ions rearrange via cyclic ions and then reopen to different linear ions. This leads to incorrect sequence information. In this proposal, I will examine the structures of unusual ions formed in the fragmentation of protonated peptides using a combination of mass spectrometry, molecular modeling and infrared spectroscopy. Theory will provide insights into mechanisms by which these ions fragment and/or rearrange.