Dynamic light scattering from small particles: Expected accuracy in hemoglobin data reduction

Dynamic light scattering from protein solutions can be applied to the detection of conformational changes and to the measurement of particle sits. Because accurate results can be adversely affected by experimental perturbations, careful procedures are necessary both in data acquisition and in data analysis. Autocorrelation functions (ACF's) of scattered light are simulated here to evaluate the role of the perturbations affecting measured signals from dilute protein solutions. The analysis of measured and simulated ACF's has been performed both by cumulant expansion and by a nonlinear least-squares fit, thereby allowing the definition of criteria for the optimization of the fitting parameters and of the measuring conditions. Moreover, by comparing experimental data from hemoglobin solutions and computer simulations, we show how to evaluate the contributions of polydispersity and statistical noise affecting the measurements. (C) 1996 Optical Society of America