Question

Explain the difference between SDS-PAGE and PAGE.In your explanation, be sure to explain why you need SDS for polyacrylamide gel electrophoresis and describe the advantages of both techniques?

Answer 1

SDS-PAGE is termed as Sodium dodecyl sulphonate- polyacrylamide gel electrophoresis. In SDS-PAGE, sds is added in the running buffer and in the gel. Sds is an anionic surfactant. Sds denatures proteins and exposés the hydrophobic patches of the proteins and coats the proteins with a net negative charge. So, in SDS-PAGE all of the proteins are denatured and negatively charged. So, here all of the proteins are separated from each other on the basis of their molecular weights.

While PAGE is termed as polyacrylamide gel electrophoresis. This is also considered as native PAGE. Sds is absent here. So, neither the proteins are denatured nor they are negatively charged. Here, proteins maintain their natural forms.

Sds is needed for better separation of proteins based on only molecular weights. Presence of sds also helps to separate the subunits of the proteins. As sds helps in better separation of proteins from each other, SDS-PAGE gel is used for Western blotting for determination of presence of any specific protein.

But in SDS-PAGE proteins lose their own natural forms and are denatured. But in PAGE as proteins maintain their natural forms, complex formation by them can be studied in PAGE. From analysis of PAGE we can say which of the proteins form complex with other proteins.

In PAGE, proteins also maintain their biological activity. So, catalytic activity can also be checked of enzymes.