The Rise of Mass Spectrometry and the Fall of Edman Degradation
Featured Article: Shevchenko A, Wilm M, Vorm O, Mann M. Mass spectrometric sequencing of proteins from silver stained polyacrylamide gels. Anal Chem 1996;68:850 -8. 2 Many of today's key proteins in biology and biomedicine were originally identified by protein chemical methods. Frederick Sanger obtained his first Nobel Prize for determining the sequence of insulin in the 1950s, and the Edman degradation, in which one amino acid after another is cleaved off the end of a protein or peptide and
... n or peptide and identified by HPLC, reigned supreme into the 1990s. My background is in mass spectrometry (MS), 3 in particular electrospray ionization (1 ), for which my advisor John Fenn won a Nobel Prize. On coming to the European Molecular Biology Laboratory (EMBL) in Heidelberg as a young group leader, I was determined to challenge what I saw as the old-fashioned chemical methods with high-tech and cool MS technology. Little did I know what I was up against, because this would require not only highly sensitive peptide sequencing by MS but also doing something with the short amino acid sequences we were able to obtain. We solved these problems by developing a highly sensitive nanoelectrospray method (2 ) and by using a peptide sequence tag algorithm (3 ), with which we could locate the proteins in the newly available DNA sequence databases. This left the pesky issue of actually getting the proteins out of the polyacrylamide gels in which biologists were always isolating them. It was accepted that once proteins were in a gel, nothing could resurrect them for MS analysis, much less high-sensitivity MS analysis. This was thought to be doubly true when the proteins were not visualized by Coomassie blue but by 10-to 100-fold more sensitive silver staining, which presumably chemically oxidized or otherwise destroyed the proteins.