Effect of Anionic Detergents on the Optical Rotatory Dispersion of Proteins

From the ¹ From the University of Texas, M. D. Anderson Hospital and Tumor Institute, Department of Biochemistry, Section of Protein Structure, Houston, Texas 77025

The ultraviolet Cotton effects of a group of proteins were investigated. Conformational transitions were effected by treating the proteins with decyl and dodecyl sodium sulfates and acid. Whereas the Cotton effects of aldolase, growth hormone, and myoglobin were not significantly altered by the treatment with detergent, considerable changes were observed in the rotatory dispersion curves of alcohol dehydrogenase, deoxyribonuclease, ß-lactoglobulin, acid solutions of ovalbumin, histone Fractions F1 and F2b, and soybean trypsin inhibitor. The curves of native alcohol dehydrogenase, deoxyribonuclease, and ß-lactoglobulin had negative minima at 228 to 230 mµ and positive maxima at 202 to 205 mµ, indicating the presence of the ß conformation. Upon treatment with detergents, the positive maxima were shifted to 198 to 200 mµ, and the amplitudes of both the positive and negative Cotton effects were increased. Changes of a somewhat similar nature were observed upon treating acid solutions of lysozyme and ovalbumin with detergents. In the instance of glutamic dehydrogenase, the changes were complex. The histones and soybean trypsin inhibitor, when in the native state, displayed curves indicating primarily disorganized polypeptide chains; these were converted by the detergents into partial -helical conformation, as judged from the rotatory dispersion curves.

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