Two-dimensional polyacrylamide gel electrophoresis of ribosomal proteins in the nanogram range

A two-dimensional gel electrophoresis system to identify and check the purity of ribosomal proteins from different organisms with nanogram quantities is described. This procedure combines the method of Geyl et al. for the separation of ribosomal proteins of Escherichia coli, and the microscale electrophoresis system for proteins described by Neuhoff and Poehling, with several modifications. The first gel dimension is carried out in capillaries and the second in the form of slab gels, both are run in newly designed chambers suitable for 10-20 samples. This electrophoresis system enables a reduction of the running time from 2 days to 2 hours and an increase in sensitivity, with Coomassie blue staining, from 3-5 micrograms for the normal 100 X 100 mm gels to 50-100 ng. The resolution of all ribosomal proteins on the micro-gel (30 X 38 X 0.5 mm) is similar to the separation on the mini-gel of 100 X 100 X 3 mm as described by Geyl et al.