Chevron Plot - Chevron Roll-overs

Chevron Roll-overs

Though the limbs of the chevron are assumed to be linear with denaturant concentration, it is not always the case. Non-linearities are usually observed in the either both the limbs or one of them and are termed chevron roll-overs. The reason for such an observation is not clear. Many interpretations including on-pathway intermediates, dead-time limitations, transition state movements (Hammond effect), aggregation artifacts, downhill folding, and salt-induced Debye-Huckel effects have been proposed to explain this behavior. In many cases the folding limb roll-overs are ignored as they occur at low denaturant concentrations, and the data is fit to a two-state model with a linear dependence of the rates. The folding rates reported for such proteins in the absence of denaturants are therefore an over-estimation.