Question

Why are proteins water soluble and why do they become not water soluble after denaturation?

Answer 1

• Proteins are build up out of amino acids. All amino acids have a similar backbone structure but differ in their side chains. These side chains have different properties, some are hydrophobic (not water-soluble) whereas others are hydrophilic (water-soluble).
• To form a functional protein, the amino acid chain is folded in a way that the hydrophobic parts end up on the inside and the hydrophilic parts on the outside. This way a stable, water-soluble protein is formed.
• Denaturation changes the 3D shape of proteins and (parts) will unfold. This way some hydrophobic side chains, usually buried inside the protein, are exposed. The protein is then not soluble anymore.