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Updated: Jan 11, 2026

Sedimentation Equilibrium of a Small Oligomer-forming Membrane Protein: Effect of Histidine Protonation on Pentameric Stability
Published on: April 2, 2015
How the protein concentration affects unfolding curves of oligomers
1Dipartimento di Biochimica e Biofisica and CRISCEB, Seconda Università di Napoli, via Costantinopoli 16, 80138 Naples, Italy. ragone@unina2.it
Abstract:
The position of unfolding curves of oligomeric proteins depends on the protein concentration. The extent of this dependence is analyzed here in terms of the midpoint concentration, i.e., the denaturant concentration at which the fractions of folded and unfolded protein are equal. Reexamination of published data highlights that the midpoint concentration decreases as the protein concentration becomes lower, as expected. Moreover, there are differences between urea and guanidine hydrochloride, as well as discrepancies between the linear extrapolation model and the denaturant binding model. These discrepancies could be used to choose the denaturation model that best fits experimental data. The equations used can be applied to any oligomeric system to check the validity of the two-state assumption.
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