We analyzed the backbone fragmentation behavior of tryptic peptides of a four-protein mixture and of E. coli lysate subjected to ultraviolet photodissociation (UVPD) at 213 nm on a commercially available UVPD-equipped tribrid mass spectrometer. We obtained 15 178 unique high-confidence peptide UVPD spectrum matches by recording a reference beam-type collision-induced dissociation (HCD) spectrum of each precursor, ensuring that our investigation includes a broad selection of peptides, including those that fragmented poorly by UVPD. Type a, b, and y ions were most prominent in UVPD spectra, and median sequence coverage ranged from 5.8% (at 5 ms laser excitation time) to 45.0% (at 100 ms). Overall, the sequence fragment intensity remained relatively low (median: 0.4% (5 ms) to 16.8% (100 ms) of total intensity), and the remaining precursor intensity, high. The sequence coverage and sequence fragment intensity ratio correlated with the precursor charge density, suggesting that UVPD at 213 nm may suffer from newly formed fragments sticking together due to noncovalent interactions. The UVPD fragmentation efficiency therefore might benefit from supplemental activation, as was shown for ETD. Aromatic amino acids, most prominently tryptophan, facilitated UVPD. This points to aromatic tags as possible enhancers of UVPD. Data are available via ProteomeXchange with identifier PXD018176 and on spectrumviewer.org/db/UVPD-213nm-trypPep.

中文翻译：

---

胰蛋白酶肽骨架在 213 nm 处的紫外光解离。


我们在市售的配备 UVPD 的三联体质谱仪上分析了四蛋白混合物的胰蛋白酶肽和在 213 nm 处进行紫外光解离 (UVPD) 的大肠杆菌裂解物的主链断裂行为。通过记录每个前体的参考光束型碰撞诱导解离 (HCD) 光谱，我们获得了 15 178 个独特的高置信度肽 UVPD 光谱匹配，确保我们的研究包括广泛的肽选择，包括那些通过 UVPD 破碎效果较差的肽。 a、b 和 y 型离子在 UVPD 光谱中最为突出，中位序列覆盖范围为 5.8%（激光激发时间为 5 ms）至 45.0%（激光激发时间为 100 ms）。总体而言，序列片段强度仍然相对较低（中位值：总强度的 0.4%（5 ms）至 16.8%（100 ms）），而剩余的前体强度较高。序列覆盖度和序列片段强度比与前体电荷密度相关，表明 213 nm 处的 UVPD 可能会因非共价相互作用而导致新形成的片段粘在一起。因此，正如 ETD 所示，UVPD 碎片效率可能会受益于补充激活。芳香族氨基酸，尤其是色氨酸，促进 UVPD。这表明芳香标签可能是 UVPD 的增强剂。数据可通过 ProteomeXchange 获取，标识符为 PXD018176，并可在spectrumviewer.org/db/UVPD-213nm-trypPep 上获取。