Question

. Regarding the folded and unfolded states of a protein (2 pt): a. Do they have the same peptide bonds? b. Do they have the same non-covalent interactions? c. Which state has more water-exposed non-polar side chains? d. Which state has higher enthalpy? Why? e. Which state has higher entropy if we consider the surrounding water molecules? Why?

Answer 1

A)

Peptide bonds are the bonds formed between the adjacent Amino Acids of a protein. In the folded as well as the unfolded state, the protein molecule has the same peptide bonds.

B)

Folded and unfolded protien molecules do not have the same non-covalent interactions. Non-covalent interactions play a major role in the stability of protein molecules in their folded state. These non-covalent interactions are absent in the unfolded state.

C)

The unfolded state has more non-polar side chains. The unfolded protein molecule has no fixed conformational structure and therefore has all side chains, regardless of polarity exposed to the surrounding solvent.

D)

The folded state has lower Enthalpy. This is because the folded state results from stabilized interactions between conformational neighbors. This interaction allows the protein to lower its internal energy. On the other hand, the unfolded state has higher enthalpy as various groups that make up the peptide are free to move about and have higher potential energy.

E)

If solely the protein is considered, then the unfolded state has higher entropy. However, the folded state along with the surrounding water molecules has higher, overall entropy. This is because the process of folding decreases the overall energy level of the folded state by increasing the entropy of the surrounding water.