How Do Salt Solutions Affect Egg White Protein Structure?

[Jordan_]

Hey, I have some homework questions and I'd appreciate some clarification.

As a class we did an experiment where we put egg white into seven different test tubes, and then introduced seven different solutions, one to each test tube. The different solutions were weak & strong salt solutions, weak base (ammonia), strong base (sodium hydroxide), weak acid (acetic acid), strong acid (hydrochloric acid), and acetone.

For the strong and weak salt solutions, nothing really happened at all, except that for the weak salt solution, the protein stayed near the bottom of the mixture and in the strong solution the protein stayed near the top. In the weak base, the protein stayed near the bottom and the top was very clear liquid. In the strong base, the protein denatured into thick white stuff. In the weak acid, the protein did not really denature as far as I saw, just stayed at the bottom of the test tube with clear liquid above it. On the strong acid, the protein again denatured. In the acetone solution, it was clear on top, denatured protein in the middle, and egg white protein on the bottom.

I am thinking the reason it denatured had something to do with peptide bonds holding amino acids together breaking and then reassembling different ways, creating the thick white gel stuff. I just don't really know how to explain this. Can you guys give me any tips on where to start looking because I'm sort of lost.

Thanks in advance.

 

[iansmith]

You should look in another direction. Try to look at the effect of the side chain of the amino acid and the charge of the polypeptides on tertiary structure.

 

[Jordan_]

Okay, I've got most of my research done. I just need to know how does the weak and strong salt solutions alter the structure? I've seen it listed in places that it works the same way as acids and bases, but it never really goes on to explain how. I really need to know how to understand this.

Thanks in advance.