Influence of a Hydroxyl Group on the Deamidation and Dehydration Reactions of Protonated Asparagine-Serine Investigated by Combined Spectroscopic, Guided Ion Beam, and Theoretical Approaches
Influence of a Hydroxyl Group on the Deamidation and Dehydration Reactions of Protonated Asparagine-Serine Investigated by Combined Spectroscopic, Guided Ion Beam, and Theoretical Approaches
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通过结合光谱、引导离子束和理论方法研究羟基对质子化天冬酰胺-丝氨酸脱酰胺和脱水反应的影响
DOI：
10.1021/jasms.0c00468
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发表时间：
2021
影响因子：
3.2
通讯作者：
Armentrout, P. B.
中科院分区：
文献类型：
--
作者：
Boles, Georgia C.;Kempkes, Lisanne J.;Martens, Jonathan;Berden, Giel;Oomens, Jos;Armentrout, P. B.
天冬酰胺肽的脱酰胺是一种自发的翻译后修饰，在生理条件下的退行性疾病和其他生物学过程中起着重要作用。在气相中，质子化肽的脱酰胺是碰撞诱导解离活化后的主要碎片化通道。在这里，我们提出了一个完整的描述从质子化的天冬酰胺-丝氨酸，[AsnSer+H]+，通过红外（IR）作用光谱和阈值碰撞诱导解离（TCID）实验结合理论计算的脱酰胺过程。IR结果表明，脱酰胺通过分叉反应途径导致呋喃酮和琥珀酰亚胺型产物离子结构，与人口分析表明后者的产品占主导地位。理论表明，肽基酰胺氧亲核攻击到Asn侧链上导致呋喃酮形成，而肽基酰胺氮亲核攻击到Asn侧链羰基碳上导致琥珀酰亚胺产物结构的形成。TCID实验发现，呋喃酮形成的阈值能量为145 ± 12 kJ/mol，琥珀酰亚胺形成的阈值能量为131 ± 12 kJ/mol，与理论能量和光谱结果一致，表明琥珀酰亚胺占主导地位。结果提供了有关的Ser侧链上的脱酰胺过程中的诱导和空间位阻效应的信息。在[AsnSer+H]+的TCID实验中观察到的另一个主要通道是脱水，其中确定的阈值能量为104 ± 10 kJ/mol。还提供了该途径的完整IR和理论分析。至于脱酰胺，发现了一个分叉途径，主要的恶唑啉和次要的二酮哌嗪产品。在这里，Ser侧链直接参与两种途径。
Deamidation of asparaginyl (Asn) peptides is a spontaneous post-translational modification that plays a significant role in degenerative diseases and other biological processes under physiological conditions. In the gas phase, deamidation of protonated peptides is a major fragmentation channel upon activation by collision-induced dissociation. Here, we present a full description of the deamidation process from protonated asparagine-serine, [AsnSer+H]+, via infrared (IR) action spectroscopy and threshold collision-induced dissociation (TCID) experiments in combination with theoretical calculations. The IR results demonstrate that deamidation proceeds via bifurcating reaction pathways leading to furanone- and succinimide-type product ion structures, with a population analysis indicating the latter product dominates. Theory demonstrates that nucleophilic attack of the peptidyl amide oxygen onto the Asn side chain leads to furanone formation, whereas nucleophilic attack by the peptidyl amide nitrogen onto the Asn side-chain carbonyl carbon leads to the formation of the succinimide product structure. TCID experiments find that furanone formation has a threshold energy of 145 ± 12 kJ/mol and succinimide formation occurs with a threshold energy of 131 ± 12 kJ/mol, consistent with theoretical energies and with the spectroscopic results indicating that succinimide dominates. The results provide information regarding the inductive and steric effects of the Ser side chain on the deamidation process. The other major channel observed in the TCID experiments of [AsnSer+H]+is dehydration, where a threshold energy of 104 ± 10 kJ/mol is determined. A complete IR and theoretical analysis of this pathway is also provided. As for deamidation, a bifurcating pathway is found with both dominant oxazoline and minor diketopiperazine products identified. Here, the Ser side chain is directly involved in both pathways.