What is the difference between PAGE and SDS-PAGE?

The major difference between native PAGE and SDS-PAGE is that in native PAGE, the protein migration rate is dependent on both the mass and structure, whereas in SDS-PAGE, the migration rate is determined only by protein’s mass.

In native PAGE, protein samples are prepared in a non-denaturing and non-reducing buffer. Therefore, in addition to the size of protein, the secondary, tertiary as well as quaternary structure all has an impact on the migration.

In SDS-PAGE, an excessive amount of SDS is added to coat proteins in negative charge, which covers all the intrinsic charges of protein. A similar charge-to-mass ratio is obtained for all proteins, and the electrophoretic mobility in SDS-PAGE depends almost solely on the size of protein.