Folding of carp parvalbumin studied by equilibrium and kinetic circular dichroism spectra

The reversible equilibrium unfolding of carp parvalbumin III (pI = 4.25) when treated with guanidine hydrochloride and the kinetics of folding and unfolding induced by concentration jump of the denaturant have been studied by the peptide circular dichroism spectra at pH 7.0 and 4.5 degree C. In the kinetic refolding reaction, a transient folding intermediate was found to be rapidly accumulated within the dead time of the stopped-flow circular dichroism (18 ms). The preequilibrium unfolding curve corresponding to the unfolding curve of the transient intermediate was obtained by measuring the refolding kinetics at various concentrations of the denaturant.