During denaturation, which level of protein structure remains unchanged?

Step-by-step solution

Denaturation of a protein involves the disruption of its secondary, tertiary, and quaternary structures due to the breaking of non-covalent interactions such as hydrogen bonds, hydrophobic interactions, and disulfide bridges. The primary structure, which is the sequence of amino acids linked by strong covalent peptide bonds, is not affected by denaturation and remains intact. Answer: primary