Peptides and proteins are coded for by genes but are often post-translationally modified at their termini or on specific amino acid side chains. These different 'chemical species' are responsible for the wide variety of functions in living organisms. In addition, the relationship between gene expression and protein expression is often poor. Mass spectrometry is a unique technique that can measure precise masses to determine the primary sequence of a protein (identification) and the modifications (relating function).
Current work focuses on the identification of proteins at sub-microgram levels (silver stain and lower) and the characterization of post-translational modifications leading to function. This task primarily starts with high quality 2D gels followed by digestion and mass spectrometry. Other methods are being explored to work on complex mixtures of proteins without 2D gel separation (2D HPLC, ICAT, etc.).