193 nm UV Photodissociation Mass Spectrometry for Ubiquitin Ions with Different Charge States

In recent years,the application of ultraviolet photodissociation(UVPD)in protein top-down mass spectrometry has attracted more and more attentions. In this study,the UVPD mass spectra of ubiquitin ions with different charge states were studied by combining a 193 nm laser with a fourier transform ion cyclotron resonance(FT-ICR)mass spectrometer. Results showed that the efficiency of ion fragmentation and trapping could be improved by introducing an appropriate amount of collision gas into the analysis cell during photoly. sis. Compared with the pure b,y ions produced in collision-activated dissociation (CAD) experiments, UVPD method produced more abundant fragment ions in both intensity and diversity. For +11 ubiquitin ions,the pro. tein sequence coverage was close to 80%,which was much higher than the corresponding experimental results of CAD. However,different from the previous reports,the fragmentation coverage still showed a correlation with the charge state of the ions. For the lower charged protein ions,further research for a better dissociation efficiency and sequence coverage is still needed very much.

Automated summary

The application of ultraviolet photodissociation (UVPD) in protein top-down mass spectrometry has gained increasing attention in recent years. Results showed that introducing an appropriate amount of collision gas during photolysis in UVPD can improve ion fragmentation and trapping efficiency, generating more abundant fragment ions. The protein sequence coverage in UVPD was found to be related to the charge state of the ions, and further research is needed to improve dissociation efficiency and sequence coverage for lower charged protein ions.