ABSTRACT
In-gel digestion of proteins isolated by gel electrophoresis is one of the most important features of mass spectrometry–driven proteomics and is a pre-separation step of target proteins before one- or two-dimensional gel electrophoresis in which the proteins are separated. This chapter discusses proteins that are isolated by one- or two-dimensional electrophoresis inside the gel structure and digested in situ. In-solution protein digestion, another pre-separation step, is based on whole-extract protein digestion in solution and is applied to complex protein mixtures. Usually, tryptic protein digestion is done either in gel or in solution, although these methodologies have several drawbacks. The chapter presents protocols for in-gel tryptic digestion of proteins and peptides as a pretreatment for the identification of protein in food. The in-gel tryptic digestion of protein is a tedious and time-consuming approach, but dedicated advances have been reported in the literature.
