The precipitation kinetics of hydroxyapatite from calcium phosphate aggregates was investigated by the continuous-angle laser light-scattering technique in the systems CaCl 2 -H 3 PO 4 -H 2 O and KCl-CaCl 2 -H 3 PO 4 -H 2 O at 25 °C. The apparent molecular weights of aggregates increased with time, and precipitation of hydroxyapatite occurred in both systems. However, the radius of gyration of the aggregate was almost constant in the former system, while it increased with the increase of the molecular weight in the latter system. Fractal dimension analysis revealed that loosely distributed particles in the aggregate transformed to a three-dimensional closely packed structure during the precipitation of hydroxyapatite in the former system, while the aggregate and the crystalline particles within it increased in size with the increased density and act as growth centers of hydroxyapatite in the latter system.

The hydrodynamic radius of a membrane protein, bc 1 -complex, in aqueous solutions was investigated using a dynamic light scattering technique. The essential unit in the solutions was found to take the dimer form of bc 1 -complex molecules. The aggregates exceeding 100 nm appeared with an increase in the crystallizing reagent, PEG, and the precipitation of an amorphous phase was observed. This feature was characteristic of zinc-free solutions. When 2 mM zinc was in the solutions, large aggregates of proteins were not observed, and single crystals of bc 1 -complex directly nucleated when the PEG concentration reached a critical level. The mutual diffusion coefficient of the dimers in the zinc-free solutions decreased with an increase in the protein concentration when the concentration of PEG was constant, indicating an attractive force between molecules. When the solution contained zinc, the coefficient increased with an increase in the protein concentration, indicating a repulsive force between molecules.

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A continuous-angle laser light scattering instrument has been developed that consists of an ellipsoidal mirror and a charge-coupled device detector. Continuous and simultaneous measurement for angular dependence of scattered intensity is achieved over the wide scattering angle with high angular resolution. Data acquisition by the instrument is quite rapid compared to conventional light scattering instruments and it takes less than 1 s in most cases. Characteristics of this instrument are evaluated and static light scattering data for linear polystyrene are presented.