Which of the following structure is not affected by protein denaturation?

PROTEIN DENATURATION • In quaternary structure denaturation, protein sub-units are dissociated and/or the spatial arrangement of protein subunits is disrupted. • Primary structure, such as the sequence of amino acids held together by covalent peptide bonds, is not disrupted by denaturation. • In secondary structure, denaturation proteins adopt a random coil as they lose all regular repeating patterns such as alpha-helices and beta-pleated sheets and configuration. • Tertiary structure denaturation involves the disruption of: 1. Covalent interactions between amino acid side- chains (such as disulfide bridges between cysteine groups) 2. Non-covalent dipole-dipole interactions between polar amino acid side-chains (and the surrounding solvent) 3. Van der Waals (induced dipole) interactions between nonpolar amino acid side-chains