Final answer:
The principle of protein precipitation with non-ionic polymers like chitosan and polyethylene glycol is based on decreasing protein solubility in water by disrupting the hydration shell. This process can be reversible but may become irreversible if proteins denature.
Step-by-step explanation:
The principle of protein precipitation resulting from the addition of non-ionic polymers such as chitosan and polyethylene glycol involves the alteration of interactions between protein molecules and water. These polymers can lead to protein precipitation by decreasing the solubility of proteins in water, a process which may be called salting-out.
Through the addition of these polymers, the hydration shell of proteins can be disrupted, enhancing protein-protein interactions and leading to precipitation. This process can be seen in the salting-in and salting-out effect, where low concentrations of salts increase protein solubility (salting-in), while high concentrations of salts reduce protein-water interaction, promoting precipitation (salting-out).
Protein precipitation by non-ionic polymers is generally a reversible process under specific conditions. However, it is important to note that if the proteins are denatured during the process, it could result in irreversible precipitation. For example, heating proteins can unfold their structures, exposing hydrophobic groups that can lead to irreversible aggregation and precipitation, as seen when boiling an egg where the protein albumin is precipitated.
Nonetheless, the reversible or non-reversible nature of the precipitation largely depends on the specific conditions and nature of the proteins and polymers involved.