Thermodynamics 열과 일의 상관관계를 연구하는 학문 분야 Provides a power to deal with poorly defined system Application to Biochemistry - Protein Folding/Unfolding - Enzyme Reaction/Inhibitor Design Chapter 2. Thermodynamics and Biochemistry

1. 열역학 제 0 법칙 (Zeroth Law) “ 열평형의 법칙 ” 2. 열역학 제 1 법칙 (First Law) “ 에너지 보존의 법칙 ” 3. 열역학 제 2 법칙 (Second Law) “ Entropy 증가의 법칙 ” 4. 열역학 제 3 법칙 (Third Law) “ S -  S 0 as T-  0 “ Thermodynamics Laws A B C

System: A part of the universe chosen for study (open/close) State of the system: Clearly definable only for systems at equilibrium - Extensive Properties/Variables (volume, energy etc) - Intensive Properties/Variables (density, viscosity etc) Reversible/Irreversible 2.1 Heat, Work, Energy

Variables of Thermodynamics Heat (q):The energy transferred into or out of a system as a temperature difference. Work (w):Any other exchange of energy between a system and its surroundings Internal energy (E):The energy within the system Enthalpy (H): H= E + PV Entropy (S): A measure of disorder S=k lnW Gibbs Free Energy (G) G=H-TS

First Law of Thermodynamics W def = F*S F S

First Law of Thermodynamics

is equal to dV. For constant pressure 1L atm = J Work of increasing or decreasing a volume Work A dx P

주어진 열이 전부 내부 에너지로 변 함 E=constant 에너지 보존 H =constant 에너지 보존

2.2 Molecular Interpretation of Thermodynamic Quantities W = N!/n 1 !n 2 !n 3 !..n n ! W 1 = 6!/5!1!= 6 W 2 = 6!/1!/2!/3! = 60 W 3 = 6!/4!/2! = 15

εiεi ε1ε1 nini n1n1 Degeneracy

εiεi ε1ε1 nini n1n1

Entropy

Entropy vs Heat dq; 내부에너 지의 변화 Absorption or release of heat changes entropy

Ex1) Ex2)

For equilibrium s1 s2

∆S = CpIn(T2/T1)

∆G = G f - G i

Ex3)

Protein Thermodynamics: Folding Kinetics

Ex1) Isothermal Titration Calorimetry (ITC) The syringe rotates in place during the ITC experiment. The end of the syringe has been adapted to provide continuous mixing in the ITC cell. The plunger is computer-controlled and injects precise volumes of ligand