Which type of interaction would cause a protein to denature, or unwind, the fastest if it was removed? a. hydrophobic interaction b. disulfide bond c. hydrogen bond d. hydrophilic interaction

The answer is HYDROGEN BONDING. Protonation of the amino acid residues (when an acidic proton H + attaches to a lone pair of electrons on a nitrogen) changes whether or not they participate in hydrogen bonding, so a change in the pH can denature a protein. The change in viscosity and color is an indication that the proteins have been denatured. Factors other than heat can also denature proteins. Changes in pH affect the chemistry of amino acid residues and can lead to denaturation. Hydrogen bonding often involves these side changes.