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Investigation of Product Ions Generated by 193 nm Ultraviolet Photodissociation of Peptides and Proteins Containing Disulfide Bonds
ACS Environmental Au Pub Date : 2022-06-23 , DOI: 10.1021/jasms.2c00124
Luis A. Macias 1 , Jennifer S. Brodbelt 1
Affiliation  

Disulfide bridges are unique post-translational modifications (PTM) that contribute to protein architecture and modulate function. This PTM, however, challenges top-down mass spectrometry by cyclizing stretches of the protein sequence. In order to produce and release detectable product ions that contribute to the assignment of proteoforms, regions of a protein encapsulated by disulfide bonds require two fragmentation events: cleavage of the protein backbone and cleavage of the disulfide bond. Traditional collisional activation methods do not cleave disulfide bonds efficiently, often leading to low sequence coverage of proteins that incorporate this feature. To address this challenge, we have evaluated the fragmentation pathways enabled by 193 nm ultraviolet photodissociation (UVPD) and UVPD coupled to electron transfer dissociation for the characterization of protein structures incorporating disulfide bonds. Cleavage of disulfide bonds by either approach results in S–S and C–S dissociation products that result from a combination of homolytic cleavage and hydrogen-transfer processes. Characterization of these product ions elevates interpretation of complex top-down spectra of proteins that incorporate disulfide bonds.

中文翻译:

193 nm 紫外光解离含有二硫键的肽和蛋白质产生的产物离子的研究

二硫键是独特的翻译后修饰 (PTM),有助于蛋白质结构和调节功能。然而,这种 PTM 通过循环蛋白质序列的延伸来挑战自上而下的质谱分析。为了产生和释放有助于蛋白型分配​​的可检测产物离子,被二硫键包裹的蛋白质区域需要两个片段化事件:蛋白质骨架的切割和二硫键的切割。传统的碰撞激活方法不能有效地切割二硫键,通常会导致包含此特征的蛋白质的序列覆盖率低。为了应对这一挑战,我们已经评估了 193 nm 紫外光解离 (UVPD) 和 UVPD 与电子转移解离相结合的碎裂途径,用于表征包含二硫键的蛋白质结构。任何一种方法对二硫键的裂解都会产生 S-S 和 C-S 解离产物,这是由均裂裂解和氢转移过程的组合产生的。这些产物离子的表征提高了对包含二硫键的蛋白质的复杂自上而下光谱的解释。
更新日期:2022-06-23
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