oiled coils are protein domains that lead to the formation of multimers (dimers, trimers, tetramers, etc.). They are found in a wide range of proteins. Here we will consider the trimerization reaction. We may write the chemical equilibrium as 3 M(aq) ⇄ T(aq) where M and T represent, respectively, the monomer and trimer species. Given that ∆rG0 = −25.00 kJ mol−1 at 37 0C (with the standard state the normal one for reactions in solution, namely c 0 = 1.0 mol dm−3 ): A) What is the equilibrium constant for the formation of the trimer at 37 0C? B) Suppose that in a particular experiment at 37.00 0C the initial concentrations of the monomer if [M]0 = 2.00×10−2 µM and the initial concentration of the trimer is also [T]0 = 2.00 × 10−2 µM. What is ∆rG for the formation of the trimer at the specified temperature? C) For the conditions given in part (B) will trimers spontaneously convert to monomers? Give a very short justification of your answer. D) Suppose that ∆rH0 and ∆rS 0 are independent of the temperature, with ∆rH0 = −29.00 kJ mol−1 at 37.00 0C. What is the value of ∆rG0 at 275 K? Note: In fact ∆rH0 and ∆rS 0 for protein unfolding typically do depend on temperature because ∆rC 0 p,m of unfolding is large and positive.

Coiled coils are protein domains that lead to the formation of multimers (dimers,
trimers, tetramers, etc.). They are found in a wide range of proteins. Here we will
consider the trimerization reaction. We may write the chemical equilibrium as
3 M(aq) ⇄ T(aq)
where M and T represent, respectively, the monomer and trimer species. Given that
∆rG0 = −25.00 kJ mol−1 at 37 0C (with the standard state the normal one for reactions
in solution, namely c
0 = 1.0 mol dm−3
):
A) What is the equilibrium constant for the formation of the trimer at 37 0C?

B) Suppose that in a particular experiment at 37.00 0C the initial concentrations of
the monomer if [M]0 = 2.00×10−2 µM and the initial concentration of the trimer
is also [T]0 = 2.00 × 10−2 µM. What is ∆rG for the formation of the trimer at
the specified temperature?

C) For the conditions given in part (B) will trimers spontaneously convert to monomers?
Give a very short justification of your answer.

D) Suppose that ∆rH0 and ∆rS
0 are independent of the temperature, with ∆rH0 =
−29.00 kJ mol−1 at 37.00 0C. What is the value of ∆rG0 at 275 K?

Note: In fact ∆rH0 and ∆rS
0
for protein unfolding typically do depend on temperature
because ∆rC
0
p,m of unfolding is large and positive.