Question

1. THE AMAZING EFFECT OF PRESSURE ON PROTEIN UNFOLDING (0.5 + 0.5 + 0.5 + 0.5 + 1 + 2 = 5 pts) a. Write down the total differential of G as a function of its natural variables T,P and N. b. From this expression, deduce an expression for   . G    P T,N c. Modify this expression upon considering a 2-state biomolecular unfolding process (from the native state N to the unfolded state U) under standard-state conditions and write down an expression for NU   G o . This simple expression is very powerful because it explains     P T,N the effect of pressure on protein unfolding processes. d. Now, consider that all experiments performed on earth so far showed that increases in pressure shift the unfolding equilibrium to the right. In other words, high pressure unfolds proteins. Based on this observation, what is the sign of NU   G o , positive or negative?     P T,N e. Based on the results in part d, is the thermodynamic volume V of the unfolded state larger U or smaller than the thermodynamic volume of the native state N V ? f. The result of part e of this question is really interesting. Very briefly explain the origin of this amazing finding (that is: VN > VU or VN < VU) based on your reading of the article by J. Roche et al. Proc. Natl. Acad. Sci. USA 109, 6945-6950 (2012). This article has been uploaded on CANVAS.

          1.  THE AMAZING EFFECT OF PRESSURE ON PROTEIN UNFOLDING
(0.5 + 0.5 + 0.5 + 0.5 + 1 + 2 = 5 pts)
a.  Write down the total differential of G as a function of its natural variables T,P and N.
b.  From this expression, deduce an expression for

 .
G 

 P
T,N
c.  Modify this expression upon considering a 2-state biomolecular unfolding process (from
the native state N to the unfolded state U) under standard-state conditions and write down an expression for  NU 

G o
. This simple expression is very powerful because it explains
 

 P
T,N
the effect of pressure on protein unfolding processes.
d.  Now, consider that all experiments performed on earth so far showed that increases in
pressure shift the unfolding equilibrium to the right. In other words, high pressure unfolds proteins. Based on this observation, what is the sign of  NU


G o
, positive or negative?
 

 P
T,N
e.  Based on the results in part d, is the thermodynamic volume
V  of the unfolded state larger
U
or smaller than the thermodynamic volume of the native state  N V ?
f.  The result of part e of this question is really interesting. Very briefly explain the origin of
this amazing finding (that is: VN > VU or VN < VU) based on your reading of the article by
J. Roche et al. Proc. Natl. Acad. Sci. USA 109, 6945-6950 (2012). This article has been
uploaded on CANVAS.

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