Question

1. A researcher is working with a protein that contains four subunits of differing molecular weights. If the researcher performs SDS-PAGE, how many distinct bands should he or she see on the gel?

2. How can you test the efficiency of protein transfer in a Western blot? (Hint: there is a type of protein staining that can be done.)

Answer 1

1. SDS PAGE is denaturing gel. It will denature the protein hence separating all four subunits. If these subunits are of a different size then there would be four different bands on the gel.

2. Post transfer the SDS PAGE gel can be stained with Coomassie stain to visualize the protein remained on the gel after the transfer. We can not stain the gel with Coomassie before transfer as this dye is irreversible. Copper dyes can be used for visualisation before the transfer.