Proteins and Enzymes

ID #1624

If a protein contains no covalent bonds in its tertiary or quaternary structure, which of the following could not happen when it denatures? Incorrect: Dissociation of hydrophobic clusters Correct: Hydrolysis Incorrect: Breaking of hydrogen bonds Incorrect: Unraveling of alpha helicies Incorrect: Disruption of ionic bonds What is the reasoning behind this question's answer?


The fact that the question mentions no covalent bonds in tertiary or quaternary structure is important, because it means that there are no disulfide bridges that need to be broken. That means that to denature this protein, you need to remove all the stabilizing forces and "unwind" the protein down to its primary sequence. That's what it means to denature a protein. Those stabilizing forces (the non-covalent ones) are H-bonds, ionic bonds, hydrophobic interactions, and van der Waal's forces. If you treat the protein so harshly that you break a peptide bond, you've gone beyond denaturing. So the reason the correct answer to your version of the question was "hydrolysis" is because hydrolyzing an existing covalent bond in this protein goes beyond denaturing.

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