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Re: SDS-PAGE mobility phosphopeptides
>Is there anybody why phosphorylated protein migrates slowly than
>dephosphorylated protein on SDS/PAGE?
The major reason is that the phosphorylation induces a structure on
the protein. Migration through the pores of the gel depends on the protein
forming an "ideal" random coil--anything that perturbs this random coil
structure, such as phosphorylation or formation of a disulfide bond, will
cause the protein to run slower (or shift up). The specific pore structure
of the gel will affect the degree of gel shifting. That is why a different
amount of cross-linker is used in gels where one is trying to detect gel
The presence of phosphate can also prevent SDS from associating
with the protein properly, but this probably requires a lot of phosphate
added to be significant.