You are trying to determine information about the structure of a protein that you have purified. You carry out a series of experiments on this protein. The results are listed below.
1. Size exclusion (aka gel filtration) chromatography of the protein indicates an apparent molecular weight of 240,000 kDa.
2. SDS polyacrylamide gel electrophoresis of the protein carried out WITHOUT the addition of a disulfide-bond reducing agent shows the protein as having an apparent molecular weight of 60,000 kDa.
3. After treatment with performic acid, which cleaves disulfide bonds, the same technique (SDS PAGE) reveals two bands of molecular weights 34,000 kDa and 26,000 kDa.
4. N-terminus identification shows Ala and Leu as amino terminal residues, in equal amounts.
Describe what you can determine about the protein's structure from the above information by answering the questions below.
a. Molecular weight of the native functional protein.
b. Does the protein contain any disulfide bonds? If yes, can you estimate how many ?
c. Can you determine anything about any secondary structure of the protein? If yes, what?
d. Does the protein have quaternary structure? If yes, how many subunits, of what size?