You are measuring the equilibrium constant for a drug

Chapter , Problem 1DE

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Problem 1DE

Problem

You are measuring the equilibrium constant for a drug candidate binding to its DMA target over a series of different temperatures. You chose your drug candidate based on computer-aided molecular modeling, which indicates that the drug molecule likely would make many hydrogen bonds and favorable dipole-dipole interactions with the DMA site. You perform a set of experiments in buffer solution for the drug-DNA complex and generate a table of Ks at different 7s. (a) Derive an equation that relates equilibrium constant to standard enthalpy and entropy changes. (Hint: equilibrium constant, enthalpy and entropy are all related to free energy), (b) Show how you can graph your K and 7data to calculate the standard entropy and enthalpy changes for the drug candidate + DMA binding interaction, (c) You are surprised to learn that the enthalpy change for the binding reaction is close to zero, and the entropy change is large and positive. Suggest an explanation and design an experiment to test it. (Hint: think about water and ions), (d) You try another drug candidate with the DMA target and find that this drug candidate has a large negative enthalpy change upon DMA binding, and the entropy change is small and positive. Suggest an explanation, at the molecular level, and design an experiment to test your hypothesis