Electric properties of macromolecules. VIII. Kerr constants and rotational diffusion of some proteins in water and in glycerol—water solutions

Kerr constants and birefringence relaxation times were measured on gamma‐globulin (I) in aqueous solution and on bovine serum albumin (II), beta‐lactoglobulin (III), ovalbumin, (IV), ribonuclease (V), lysozyme (VI), and chymotrypsin (VII) in glycerol–water solutions. Rotational diffusion constants were calculated from the data and were compared with those calculated from the protein dimensions obtained by other methods. The calculated and observed rotational diffusion constants were in excellent agreement for I, IV, V, and VII, and were within a factor of two for III. VI showed evidence of aggregation and II gave a low relaxation time in glycerol–water solution, apparently because of a structural change or a localized solvent viscosity effect. The earlier results for maximum dimensions based upon the dielectric relaxation time method were found to be in agreement with present findings in a number of instances, in spite of the possible complication of the dielectric method by ionic polarization effects.