The high concentration of urea causes unfolding of protein and thus results in loss of function of a protein. The urea interacts with the protein and prevents the folding of a protein.
During oxidation, the disulfide bonds that are required for proper functioning and stabilization of protein are formed, while in the presence of urea, the disulfide bonds are not positioned correctly. The protein oxidation results in covalent modification of a protein that results in the change of physical and chemical properties of a protein.
The change of physical and chemical properties of protein after oxidation and in the presence of urea cannot be modified even after the removal of urea. Thus, protein does not fold properly.
Hence the right answer is "disulfide bonds are not positioned correctly rather than week bonding interaction"
