Distinguishing between smooth and rough free energy barriers in protein folding.
Analysis of curved chevron plots is a powerful tool in investigating protein folding pathways, as the curvatures can be used to gain information about both early and late folding events. When and if accumulation of low-energy intermediates can be ruled out, two different models have classically been applied to describe curved chevron plots, namely , (i) Hammond effects along smooth barrier profiles and (ii) changes in the rate-limiting step between two discrete transition states. The two models lead to very similar numerical solutions, which are generally indistinguishable. This is not surprising, since the smooth barrier assumption approximates barrier profiles with a more complex topology involving multiple local maxima that are too close, or too broad, to yield clear-cut kinks in the chevron data. In this work, we have reconstructed the transition state shifts as a function of protein stability over a wide stability range for three small globular proteins, to screen for fingerprints more sensitive for different barrier profiles. We show that such an analysis represents a valuable test for the discrimination between the two different scenarios.
Gianni
Stefano
S
Istituto Pasteur-Fondazione Cenci Bolognetti, Dipartimento di Scienze Biochimiche A. Rossi Fanelli, Università di Roma La Sapienza, Rome, Italy.
Brunori
Maurizio
M
Jemth
Per
P
Oliveberg
Mikael
M
Zhang
Mingjie
M
D000076122:Disks Large Homolog 4 Protein; D004734:Energy Metabolism / Q000235:genetics / Q000502:physiology*; D006801:Humans; D047908:Intracellular Signaling Peptides and Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D007700:Kinetics; D008565:Membrane Proteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D016297:Mutagenesis, Site-Directed; D054731:PDZ Domains / Q000235:genetics / Q000502:physiology*; D010750:Phosphoproteins / Q000737:chemistry / Q000378:metabolism / Q000502:physiology; D011489:Protein Denaturation / Q000235:genetics; D017510:Protein Folding; D015398:Signal Transduction / Q000235:genetics / Q000502:physiology*; D062826:Zonula Occludens-1 Protein
C501444:DLG4 protein, human; D000076122:Disks Large Homolog 4 Protein; D047908:Intracellular Signaling Peptides and Proteins; D008565:Membrane Proteins; C435927:PLEKHA1 protein, human; D010750:Phosphoproteins; C569042:TJP1 protein, human; D062826:Zonula Occludens-1 Protein