Question

One way to destabilise a folded protein structure is to change the solution conditions so that the backbone NH and CO groups in the polypeptide chain form stronger hydrogen bonds with other components of the solution (compared to the hydrogen bonds that they form with each other in the folded protein).

Which of the following perturbations is most likely to destabilise a protein in this way?

Select one:

a. Adding a high concentration of guanidine

b. Changing the pH of the solution from 7 to 13 by adding sodium hydroxide

c. Increasing the solution to a high temperature (almost boiling)

d. Adding a high concentration of sodium dodecyl sulfate (SDS)

e. Changing the pH of the solution from 7 to 1 by adding hydrochloric acid

Answer 1

d. Adding a high concentration of sodium dodecyl sulfate (SDS)

Guanidine Hydrochloride is a chaotropic agent and destabilizes proteins by decreasing the non-covalent forces taht stabilize molecules. On the other hand, increasing or decreasing the pH, or heating the protein also affects the structure by destabilizing the Hydrogen bonds that hold up the protein structure.

Senaturatuion by using SDS, however, denatures the inttramolecular non-covalent bonds, by promiting the hydration of different amino acids within the protein molecule.