OPTICAL ROTATORY DISPERSION OF HUMAN CARBONIC ANHYDRASES: COTTON EFFECTS AND AROMATIC ABSORPTION BANDS

Abstract
Carbonic anhydrases A, B, and C from human erythrocytes give unusual optical rotatory dispersion curves involving several relatively small but reproducible Cotton effects in the region between 260 and 300 m/i, associated with the absorption bands of the aromatic side chains in these proteins. When the highly compact structure of the native proteins is disrupted by denaturation in acid, urea, or guanidine hydrochloride solutions, these Cotton effects disappear. The rotatory dispersion curves for the native enzymes B and C pass through troughs at 223 and 227 mu, respectively, with values of the molar residue rotation of the order of [long dash]2300[degree] at this minimum.