A researcher heats a globular enzyme to 90 °C. After cooling, the enzyme has lost activity, and circular dichroism shows loss of secondary and tertiary structure but the polypeptide has not been cleaved. The researcher concludes the protein has been denatured.
Which interaction shown in the figure is LEAST likely to be broken by simple heating?
- A
Hydrophobic clustering
- Bcheck_circle
Covalent disulfide bond
- C
Ionic interaction
- D
Hydrogen bond
Explanation
Heat readily disrupts noncovalent interactions (H-bonds, ionic, hydrophobic) but covalent disulfide bridges typically require reducing agents to break.