Optical Rotatory Dispersion of Catalase.

It is well recognized that the measurements of optical rotatory dispersion of proteins with strong absorption bands are extremely difficult because of the diminishing intensity of the emergent light. Until very recently, these studies were made possible only by improving the light source and also frequently by a wide opening of the slit width on the monochromator at the expense of spectral purity. Unfortunately, many of the observations of Cotton effects as reported in the literat.ure were found to be merely rotatory artifacts which can easily be produced in regions of high absorbance (1). Now that better instruments are available, more accurate data on optical rotatory dispersion of proteins such as myoglobin and hemoglobin (2-4) are beginning to accumulate. In this paper, we will present the optical rotatory dispersion of both native and denatured catalase. Our results seem to differ significantly from the recent findings of Osbahr and Eichhorn (5), whose measurements perhaps suffered the handicap of instrumental limitation. With the present data, we will also estimate the helical content of catalase by various optical rotation analyses.