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3.2. THERMODYNAMICS:
IMPORTANT TOOL
IN
BIOCHEMISTRY
3.2.1. General
comments
This part of the compendium overlaps partly with chapter 10 in the textbook,
but adds new examples and simplifies or omits some of the intermediate
calculations.
Thermodynamics is a key area in all natural sciences. For biopolymers in
solution it provides a range of useful formulae allowing quantitative
descriptions of key macromolecular parameters. Thermodynamic approaches
are in particular relevant when studying:
•
Ordered and disordered conformations
•
Denaturation and renaturation
•
Solubility, precipitation, phase behaviour, swelling
•
Interactions with ions
•
Effects of added/removed salts
•
Ligand binding
•
Osmotic effects
•
M, A
2
•
Entropy of mixing
•
Methods (calorimetry/ITC, osmometry..)
•
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Note that thermodynamics applies only to systems at equilibrium. In the
biopolymers field we sometimes observe slow processes when changing the
conditions. This may sometimes lead us to believe that equilibrium has been
established when it in reality has not.
Before continuing, let us briefly repeat two key formulae from your first
chemistry courses
Δ
G
= Δ
H
−
T
Δ
S
Δ
G
0
= −
RTlnK
Make sure you understand these equations well.