Terminal proteomics: N- and C-terminal analyses for high-fidelity identification of proteins using MS.

In proteomics, MS plays an essential role in identifying and quantifying proteins. To characterize mature target proteins from living cells, candidate proteins are often analyzed with PMF and MS/MS ion search methods in combination with computational search routines based on bioinformatics. In contrast to shotgun proteomics, which is widely used to identify proteins, proteomics based on the analysis of N- and C-terminal amino acid sequences (terminal proteomics) should render higher fidelity results because of the high information content of terminal sequence and potentially high throughput of the method not requiring very high sequence coverage to be achieved by extensive sequencing. In line with this expectation, we review recent advances in methods for N- and C-terminal amino acid sequencing of proteins. This review focuses mainly on the methods of N- and C-terminal analyses based on MALDI-TOF MS for its easy accessibility, with several complementary approaches using LC/MS/MS. We also describe problems associated with MS and possible remedies, including chemical and enzymatic procedures to enhance the fidelity of these methods.