Proteins can be precipitated out of aqueous solution by the addition of an electrolyte; this process is called “salting out” the protein. A friend of yours who is taking a biochemistry class says that salting out works because the waters of hydration that surround the protein prefer to surround the electrolyte as the electrolyte is added; therefore, the protein’s hydration shell is stripped away, leading to protein precipitation. Another friend of yours in the same biochemistry class says that salting out works because the incoming ions adsorb tightly to the protein, making ion pairs on the protein surface, which end up giving the protein a zero net charge in water, and therefore leading to precipitation. Discuss these two hypotheses. What kind of measurements would you need to make to distinguish between these two hypotheses?

Verified step by step guidance

1. Step 1: Understand the concept of 'salting out' in protein chemistry. 'Salting out' is a process where proteins precipitate out of solution upon the addition of high concentrations of salt. This is due to changes in the solubility of the protein in the presence of the salt.
2. Step 2: Analyze the first hypothesis: The waters of hydration surrounding the protein prefer to surround the electrolyte. This suggests that the electrolyte competes with the protein for water molecules, leading to dehydration of the protein and subsequent precipitation.
3. Step 3: Analyze the second hypothesis: The incoming ions adsorb onto the protein surface, forming ion pairs and neutralizing the protein's charge. This implies that the protein's solubility decreases because it loses its charge, which is essential for maintaining solubility in water.
4. Step 4: Consider experimental measurements to test these hypotheses. For the first hypothesis, you could measure the hydration shell of the protein using techniques like nuclear magnetic resonance (NMR) or infrared spectroscopy to observe changes in water-protein interactions.
5. Step 5: For the second hypothesis, you could use electrophoretic mobility measurements or zeta potential analysis to determine changes in the protein's net charge as salt is added. This would help identify if the protein's charge is being neutralized by ion adsorption.