Microscale multisample two-dimensional electrophoresis of proteins in human serum, cerebrospinal fluid, and urine

In this technique, in which no denaturing agent is used, proteins in human serum, cerebrospinal fluid, and urine are separated by isoelectric focusing in cylindrical 40 g/L polyacrylamide gels of capillary size (1.3 x 35 mm) for 40 min, followed by electrophoresis in 40--170 g/L polyacrylamide linear gradient gel, with use of 38 x 35 x 1 mm slab gel, for 1 h. Only 2 microL of untreated human serum is required to obtain clear protein-distribution patterns, made visible by Coomassie Blue staining. By use of silver staining, proteins in unconcentrated cerebrospinal fluid can be made visible. An apparatus we devised for microscale two-dimensional electrophoresis enables us to analyze eight protein samples simultaneously.