Principle of 2-D Electrophoresis

• Isoelectric points and molecular weights are characteristic parameters of proteins, which are completely independent from each other
• Each protein has a specific pI and MW
• You can detect up to 5,000 protein spots in one gel

1. First dimension:
Denaturing isoelectric focusing separation according to the isoelectric point

2. Second dimension:
SDS electrophoresis separation according to the molecular weight

2-D electrophoresis resolves a few thousand protein spots.