Gas-Phase Chemistry of Biological and Metal-Containing Ions

生物离子和含金属离子的气相化学

• 批准号: RGPIN-2014-05297
• 负责人: Siu, KWMichael
• 金额: $ 3.93万
• 依托单位: University of Windsor
• 依托单位国家: 加拿大
• 项目类别: Discovery Grants Program - Individual
• 财政年份: 2015
• 资助国家: 加拿大
• 起止时间: 2015-01-01 至 2016-12-31
• 项目状态: 已结题
• 来源: https://www.nserc-crsng.gc.ca/ase-oro/Details-Detailles_eng.asp?id=588329
• 关键词: Gas; Phase; Chemistry; Biological; Metal

Advances in proteomics have been made possible by conceptual developments and technological breakthroughs in biological mass spectrometry (MS). The long-term objective of our Discovery research program will continue to aim at better understanding fundamental aspects of the science that underpins peptide and protein identification and characterization. In the shorter term, and within the duration of this funding cycle, our objectives are to explore the structure, formation, energetics and fragmentation chemistry of (1) protonated peptides ([M + H]+) and their key fragments; (2) molecular radical cations of peptides (M•+); and (3) metalated peptide complexes. These will be tackled using a combination of experimental and theoretical approaches. Experimental techniques will include: (i) tandem MS with isotopic labeling with 13C, 2H, 18O and 15N; (ii) threshold collision-induced dissociation (CID) on a modified MS instrument fitted with a ring ion guide as q2; and (iii) IRMPD spectroscopy performed in the FELIX facility. We propose herein to continually improve our understanding of the structures and dissociation chemistry of protonated peptides and their key fragments. We will start with selected a(n) product ions and their next-generation fragments formed after losing a small neutral product, such as ammonia giving a(n)*, and water giving a(n)0 ions. We will examine the effects of side-chain functional groups on the relative energetics and stability of a(2) isomers, especially those of a newly discovered imine-amide structure (L2) and a cyclic structure (C1), by performing a systematic study including basic and acidic residues. Relatively little is known about the structures of a(n)* and a(n)0 ions. Our preliminary results strongly suggest that the a(3)* and a(4)* ions of pentaalanine (A5) have unconventional structures in that they have imine-oxazolone structures. Surprisingly, the a(4)* ion of pentaglycine (G5) is not an imine-oxazolone, but a protonated imidazolone, a new class of products first proposed by us for dehydrated protonated G4, a nominal b4 ion. In addition, the IRMPD spectrum of the a(4)* ion of G5 closely resembles that of the a(4)0, thereby suggesting both structures are protonated imidazolones. We will fully explore and determine the mechanisms and energetics leading to the different isomeric products. We will continue improving our understanding of factors that determine structural stability in peptide radical ions and their fragmentation mechanisms. CID of M•+ from oligopeptides of glycine containing a single tyrosine (Y) or tryptophan (W) residue in a non-terminal position typically shows most-prominent products that originate from a proton-bound ‘dimer’ formed after cleavage of the N–C(alpha) bond of Y or W. Surprisingly, preliminary data on the CID of oligoalanines containing a single Y residue reveal additional and puzzling fragmentation channels. We plan to fully investigate these fascinating fragmentation channels by ‘moving’ Y along the oligoalanine framework and having Y as the third, fourth and subsequent residues. In addition, we will also examine CID results of the M•+ from oligoalanines containing a single W residue. We plan to continue examining multi-stage MS of metalated peptide complexes to generate unusual and fascinating peptide ions, including dispositive protonated a3 and a2 ions which have high charge-density due to their small size. We attribute the effectiveness of LaIII in generating these ions to its high charge and its propensity to delocalize its charge onto the ligand, as well as the high affinity of La for O (thereby facilitating the cleavage of COO-). We plan to extend the line of study to using Ce•3+ and other lanthanide ions as the metalation center.

蛋白质组学的发展是由生物质谱（MS）概念的发展和技术的突破而实现的。 我们的发现研究计划的长期目标将继续旨在更好地理解支持肽和蛋白质鉴定和表征的科学的基本方面。 在短期内，在本资助周期内，我们的目标是探索（1）质子化肽（[M + H]+）及其关键片段的结构，形成，能量学和断裂化学;（2）肽的分子自由基阳离子（M·+）;和（3）金属化肽复合物。 这些问题将采用实验和理论相结合的方法加以解决。 实验技术将包括：（一）串联质谱与同位素标记的13 C，2 H，18 O和15 N;（二）阈值碰撞诱导解离（CID）的改良MS仪器上安装了一个环离子导向器作为q2;和（三）IRMPD光谱在FELIX设施进行。 我们在此建议不断提高我们的质子化肽及其关键片段的结构和解离化学的理解。 我们将从选定的a（n）产物离子和它们失去小的中性产物后形成的下一代碎片开始，例如氨产生a（n）*，水产生a（n）0离子。 我们将通过包括碱性和酸性残基的系统研究，考察侧链官能团对a（2）异构体，特别是新发现的亚胺-酰胺结构（L2）和环状结构（C1）的相对能量和稳定性的影响。 关于a（n）* 和a（n）0离子的结构知之甚少。 我们的初步结果强烈地表明五丙氨酸（A5）的a（3）* 和a（4）* 离子具有非常规的结构，因为它们具有亚胺-恶唑酮结构。 令人惊讶的是，五甘氨酸（G5）的a（4）* 离子不是亚胺-恶唑酮，而是质子化咪唑酮，这是我们首次针对脱水质子化G4（名义上的b4离子）提出的一类新产物。 此外，G5的a（4）* 离子的IRMPD光谱非常类似于a（4）0的IRMPD光谱，从而表明两种结构都是质子化的咪唑酮。 我们将充分探索和确定导致不同异构产物的机理和能量学。 我们将继续提高我们对决定肽自由基离子结构稳定性的因素及其碎片化机制的理解。 来自在非末端位置含有单个酪氨酸（Y）或色氨酸（W）残基的甘氨酸寡肽的M·+的CID通常显示最显著的产物，其源自Y或W的N-C（α）键裂解后形成的质子结合的“二聚体”。 令人惊讶的是，初步数据的CID的寡丙氨酸含有一个单一的Y残基揭示额外的和令人费解的碎片通道。 我们计划通过“移动”Y沿着寡聚丙氨酸框架并将Y作为第三、第四和随后的残基来充分研究这些迷人的片段化通道。 此外，我们还将检查来自含有单个W残基的寡丙氨酸的M·+的CID结果。 我们计划继续研究金属化肽复合物的多阶段MS，以产生不寻常的和迷人的肽离子，包括由于其小尺寸而具有高电荷密度的一次性质子化a3和a2离子。 我们将LaIII产生这些离子的有效性归因于其高电荷和其将电荷离域到配体上的倾向，以及La对O的高亲和力（从而促进COO-的裂解）。 我们计划将研究范围扩展到使用Ce·3+和其他镧系离子作为金属化中心。