Identification by mass spectrometry of two-dimensional gel electrophoresis-separated proteins extracted from lager brewing yeast

As two-dimensional (2-D) electrophoresis allows the separation of several h undred proteins in a single gel, this technique has become an important too l for proteome studies and for investigating the cellular physiology. In or der to take advantage of information provided by the comparison of proteome pictures, the mass spectrometry technique is the way chosen for a rapid an d an accurate identification of proteins of interest. Unfortunately, in the case of industrial yeasts, due to the high level of complexity of their ge nome, the whole DNA sequence is not yet available and all encoded protein s equences are still unknown. Nevertheless, this study presents here 30 lager brewing yeast proteins newly identified with matrix assisted laser desorpt ion/ionization-time of flight (MALDI-TOF), tandem mass spectrometry (MS/MS) and database searching against the protein sequences of Saccharomyces cere visiae. The identified proteins of the industrial strain correspond to prot eins which do not comigrate with known proteins of S. cerevisiae separated on 2-D gels. This study presents an application of the MS technique for the identification of industrial yeast proteins which are only homologous to t he corresponding S. cerevisiae proteins.