The role of disulfide bonds in the protein structure. Conformational studies on reduced ribonuclease and lysozyme.

Circular dichroism spectra in different media of native, partially reduced, and fully reduced rihonuclease and lysozyme are reported and discussed with reference to the role of the disulfide linkages in maintaining the tertiary structure of the native enzymes. The results obtained indicate a large disorganization of the native molecules when all disulfide bridges are broken even if in both fully reduced proteins there appears to be some residual non-covalent structure. However, a tendency toward the partial recovery of the native structure is shown by the reduced proteins on decreasing the temperature or in the presence of methanol. In addition it has been found that some particular disulfide linkages are unessential for achieving the overall conformation of the molecules.