A Circular Dichroic Spectral Study on Disuffide-Reduced Pancreatic Ribonuclease A and Its Renaturation to the Active Enzyme1

Publisher Website
Google Scholar
Abstract
Disulfide-reduced RNase A, which could be reoxidized to give the native enzyme, was shown to have a CD spectrum quite different from that of the native enzyme or a random coil. Disulfide-reduced and fully cysteine-S-carboxamidomethylated RNase A was used for further CD-spectral analysis instead of unstable reduced RNase A because the derivative was stable and gave a spectrum identical to that of reduced RNase A. Curve-fitting analyses showed the presence of 14% α-helix and 25% β-structure in this open chain derivative of RNase A. The time dependence of CD spectra during the oxidative renaturation of reduced RNase A was analyzed and changes in α-helical and β-structure contents during the reaction were estimated. It was shown that the change in the content of β-structure was slower than that of α-helix content and approximately paralleled the appearance of the enzymatic activity.