Vacuum UV photodissociation tandem mass spectra of singly charged arginine-terminated phosphopeptides were recorded at times ranging from 300 ns to ms after photoexcitation, to investigate when the phosphate group falls off from the precursor and product ions and whether loss of phosphate can be eliminated in tandem mass spectra. For peptide ions containing phosphoserine and phosphothreonine, little loss of 98 Da from the product ions was observed up to 1 µs after photoexcitation. However, neutral losses from the precursor ions were considerable just 300 ns after photoactivation. Loss of 98 Da from product ions first appears about 1 µs after laser irradiation and becomes more common 13 µs after photoexcitation. Consistent with previous reports, phosphotyrosine was more stable than either phosphoserine or phosphothreonine.

在光激发后 300 ns 到 ms 的时间范围内记录单电荷精氨酸封端的磷酸肽的真空紫外光解串联质谱，以研究磷酸基团何时从母离子和产物离子脱落，以及是否可以串联消除磷酸基团的损失质谱。对于含有磷酸丝氨酸和磷酸苏氨酸的肽离子，在光激发后 1 µs 内观察到来自产物离子的 98 Da 几乎没有损失。然而，光活化后仅 300 ns，前体离子的中性损失就相当可观。子离子中 98 Da 的损失在激光照射后约 1 µs 首次出现，在光激发后 13 µs 变得更为常见。与之前的报告一致，磷酸酪氨酸比磷酸丝氨酸或磷酸苏氨酸更稳定。