When egg white is heated, it hardens and is opaque. This cooking process cannot be reversed, but hard-boiled egg white can be dissolved by heating it in a solution containing SDS (strong detergent) and 2-mercaptoethanol (reducing agent). Neither reagent alone has any effect.

a. Why does boiling an egg white cause it to harden and become opaque?

b. Why does it require both a reducing agent and a detergent to dissolve the hard-boiled egg white?

Generally proteins are denatured at high temperature. Therefore when the egg is hard boiled they are denatured since eggs are protein, the 3-dimensional structure of protein is lost, and it is replaces with tangled meshwork of polypeptide chains. This is because the orderly arrangements of disulphide bonds in proteins are disrupted, which results in the formation of inter chains bonds among disulphide bonds, making the protein molecules to link together. This explains the reason for the 3-D structure disruption and formation of a macro molecule.

However, the addition of reducing agent, breaks the covalent disulphide bonds. While detergent breaks the interchain bonds among the disulphide bonds. (The noncovalent bonds), These combined effects untangled the mesh networks of polypeptides formed, and reduces the hardened nature,