Identify the compensation temperature in enthalpy-entropy compensation. Use the
ID: 1009859 • Letter: I
Question
Identify the compensation temperature in enthalpy-entropy compensation. Use the degree of Celsius as the unit of temperature in your answer. Round your answer to one decimal point. please show work, thank you :)
Table 1: Temperatures and Enthalpies of the DSC Transitions for Human -Interferon under Several pH and Buffer Concentration Conditions T,n (°C) H(kJ/mol of dimer) 523 530 600 649 buffer concn 5 mM 4.1 4.3 4.9 6.6* b 53.9 57.5 60.6 3.0* 3.5 3.8 36.0 40.3 44.1 45.9 50.1 51.3 165 310 375 401 460 10 mM 4.1 4.3 45 503 525 547 53.8 54.9 56.0 56.9 58.3 59.5 60.2 4.9 5.3 5.8* 6.6* 7.8* 3.8* 578 606 44.6 47.2 50.8 51.8 54.3 56.8 59.0 60.1 60.2 60.2 20 mM 392 438 4.1 4.3 500 518 4.9 5.8* 6.6* 7.8* 8.8* 560 562 3.9* 45.2 46.7 48.4 54.5 60.0 50 mM 300 332 4.3* 4.9* 6.6* 4.0* 4.3* 5.7* 6.6* 7.6* 44.3 47.7 58.3 59.7 59.1 100 mM 252 401 438 pH values were measured at 25 °C and corrected to the Tm values as indicated under Experimental Procedures. Asterisks indicate that after 2 h ofExplanation / Answer
The phenomenon of entropy–enthalpy (S-H) compensation is widely invoked as an explanatory principle in thermodynamic analyses of proteins, ligands, and nucleic acids. It has been suggested that this compensation is an intrinsic property of either complex, fluctuating, or aqueous systems. The questions examined here are whether the observed compensation is extra-thermodynamic (i.e., reflects anything more than the well-known laws of statistical thermodynamics) and if so, what does it reveal about the system? Compensation is rather variably defined in the literature and different usages are discussed. The most precise and interesting one, which is considered here, is a linear relationship between H and S for some series of perturbations or changes in experimental variable. Some recent thermodynamic data on proteins purporting to show compensation is analyzed and shown to be better explained by other causes. A general statistical mechanical model of a complex system is analyzed to explore whether and under what conditions extra-thermodynamic compensation can occur and what it reveals about the system. This model shows that the most likely behavior to be seen is linear S-H compensation over a rather limited range of perturbations with a compensation temperature Tc = dH/dS within 20% of the experimental temperature. This behavior is insensitive to the details of the model, thus revealing little extra-thermodynamic or causal information about the system. In addition, it will likely be difficult to distinguish this from more trivial forms of compensation in real experimental systems.