Turbidity as a useful optical parameter to predict protein crystallizationby dynamic light scattering

The aggregation behavior of several proteins in solution including the huma n apolipoproteins A-II and C-III, as well as concanavalin A, thaumatin, lys ozyme and mexicain, is discussed based on dynamic light scattering techniqu es. According to our results, the estimation of parameters such as the geom etrical factor (H) and turbidity (tau) under different environmental condit ions, is a useful approach in order to elucidate if protein aggregation is carried out by either nucleation or random mechanisms. We conclude that dyn amic light scattering, an accurate and non-destructive technique, can be us ed to determine either protein precrystallization parameters or crystalliza tion conditions when both H and tau are taken into account. (C) 2000 Elsevi er Science B.V. All rights reserved.