A study by rotatory dispersion of the denaturation of catalase and peroxidase.

The recent applications of rotatory dispersion techniques to the study of protein structure have for the most part utilized the effect of protein conformation upon dispersion curves that are associated with ultraviolet absorption bands (l-7). The hemoproteins are unique among biologically important proteins in that they also have chromophores in the visible range of the spectrum. It has been demonstrated, in the case of cytochrome c, that these chromophores can produce a Cotton effect in the visible region (8). It is shown in the present study that catalase and peroxidase also exhibit a Cotton effect, but only under conditions in which the proteins have ordered structures. Consequently, these dispersion curves have been used in a study of the denaturation of hemoproteins with acid and base, as well as in a study of the removal of heme from catalase and the recombination of hematin with the resulting apoprotein.