5. Protein Techniques

By adding SDS to a protein and performing gel electrophoresis, it is possible to:

True or false: Protein subunits linked via disulfide bonds appear as separate bands on an SDS-PAGE gel.

Which of the following statements are true regarding the treatment of proteins with SDS?

i) Only proteins with native net charges acquire an overall net negative charge.

ii) Proteins denature due to a disruption of the hydrophobic interactions stabilizing the core of their structures.

iii) All protein subunits can be separated via SDS-PAGE.

Suppose you purify a protein from liver cells and the SDS-PAGE results after different purification steps are shown. You then take the affinity purified sample and run it through a cation exchange column.The 2^nd SDS-PAGE shows the results for the flow through and eluate from the cation exchanger. Based on this data, what conclusions can you draw from the results in lanes #5, 7 & 8?

Lane #5:

Lane #7:

Lane #8: