N-Terminal/C-Terminal sequencing

The contents of sequence analysis of protein or peptide drugs include N-terminal sequencing, C-terminal sequencing and peptide coverage analysis. The present analysis reports the determination of protein C-terminal sequence, which is based on mass-spectrographic technique. The procedure for C-terminal sequencing was once similar with N-terminal sequencing, whereas it was more complex, and the associated instruments have already been discontinued. Hence, mass spectrometry based method is currently the conventional approach for analyzing C terminal sequence of protein or peptide. After enzymatic hydrolysis, the peptide mixture is separated by UPLC and then analyzed by XevoG2-XS QTOF. According to the MS/MS result and the data analysis software, we can identify the peptides corresponding to ultraviolet absorb peak in UPLC.