HH H2 IH Het HH . pressure / GPa 7. The P-T phase diagram for a...
HH H2 IH Het HH . pressure / GPa 7. The P-T phase diagram for a protein generally has a 1.5 characteristic elliptical shape as shown on the right for Zn-Cytochrome c with experimental points (discussed in the Aside on p. 14 of the W10,11 lecture notes on phase transitions). The inside of the ellipse denotes P,T val- ues for folded states where outside are P,T values for unfolded states (P < 0 is unphysical). The ellipse itself is the equilibrium coexistence line for the folded (native) <=> unfolded (denatured) transition. a) Give the coordinates (P,T values) of the critical 500 points including any inflection points. 20 40 60 80 100 b) Use the Clapeyron equation, dp/dT = ASm/AVm to explain what the points from part a) mean in terms of ASm and AVm of the transition. c) Careful measurements at 298 K and 0.91 GPa establish that AVm for the transition is -74.6 cm3 mol-. What is ASm and AH m at this P,T? d) Answer as per part c) for AVm = 65.0 cmº mol-' at 345 K and 0.10 GPa. e) Use LeChatelier's principle and conclude which is more important, AS or AV in 1) heat unfolding, 2) pressure unfolding, and 3) cold unfolding for Zn-Cytochrome c. temperature / °C