Protein folding in the absence of a clear free-energy barrier

• Many small proteins fold in a two-state manner, the rate-limiting step being the passage of the free-energy barrier separating the unfolded state from the native one. The free-energy barrier is, however, weak or absent for the fastest-folding proteins. Here a simple diffusion picture for such proteins is discussed. It is tested on a model protein that makes a three-helix bundle. Assuming the motion along individual reaction coordinates to be diffusive on timescales beyond the reconfiguration time for a single helix, it is found that the relaxation time can be predicted within a factor of two. It is also shown that melting curves for this protein to a good approximation can be described in terms of a simple two-state system, despite the absence of a clear free-energy barrier.

Ämnesord

NATURVETENSKAP  -- Biologi -- Biofysik (hsv//swe)

NATURAL SCIENCES  -- Biological Sciences -- Biophysics (hsv//eng)

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