Quasi-Elastic Light Scattering from Solutions of Macromolecules. I. Doppler Broadening of Light Scattered from Solutions of Tobacco Mosaic Virus Particles

By use of a laser light source and photoelectric light mixing technique, spectral densities of light scattered from solutions of tobacco mosaic virus particles were measured in order to obtain translational and rotational diffusion coefficients, D and \(\), of the particle. The observed values of D 20 and \(₂₀\) are 0.29±0.01×10 -7 cm 2 sec -1 and 360±20 sec -1 , respectively, for the 3 mg/ml solution. These coefficients were markedly dependent on the protein concentration of solutions below 1 mg/ml. In addition, the intensity due to the coupling of translational and rotational Brownian motions was observed, which agreed with a theoretical prediction.