Question

Im doing a lab report testing the relationship between salt concentration and enzyme activity (turnip peroxidase). I noticed that when we added more salt, a foamy layer formed on top of the test tube; There was no foamy layer when we tested with different pH's though. Does anyone know why?

Answer 1

This is due to salting in and salting out process.

All enzymes are protein and protein have specific structure due to folding of long linear polypeptide chain. The folding of this chain is due to various bonds and interactions. The most important Bond is peptide Bond which connects two amino acid. The 3D structure of protein is due to hydrophobic interactions.

When we increase the concentration of salt the all water molecules list the protein and binds with salt molecule that is why the structure of protein is disturbed.