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A way to test a protein's stability against chemical treatment is to examine the energy involved in folding and unfolding
the protein, or the activation energy. Proteins fold the way they do in physiological conditions because they aim to
reach their lowest energy state. Changing the electrochemical composition of the surrounding environment may
increase the amount of energy a protein needs to stay in its native state. At a particular point, the protein will not be
able to resist that energy, and it will change shape or unfold to return to a lower energy state. The amount of energy
needed to unfold the protein, the activation energy, can also indicate the protein's stability: The higher the activation
energy, the lower the stability.
T
m
The unfolding transition temperature, the temperature at which 50% of the protein is unfolded
T
agg
The temperature at which the protein begins to form aggregates
T
onset
The temperature at which the protein begins to unfold
ΔG The Gibbs free energy of unfolding
E
a
The activation energy
C
m
or C
50
The concentration of a chemical denaturant that results in 50% of the protein to unfold
Laboratories interested in protein characterization use a variety of methods to detect, measure, and analyze the
chemical properties of proteins, including stability. With varying levels of sensitivity, specificity, and throughput, these
instruments can provide information about a protein's thermal and chemical stability and uncover more information
about possible regulatory roles for the target molecules.
What parameters
do I measure?
What technologies
are available to measure protein stability?
