Static and dynamic light scattering have been employed to investigate the behaviour of lysozyme solutions when varying the concentration of (NH4)2SO 4 and NaC1 for screening the repulsive forces between the monomers. At the initial aggregation stages clusters, which can be classified as mass-fractals undergoing diffusion limitedlike aggregation, coexist with monomers or small lysozyme oligomers. The kinetics of fractal growth deliver observables that exhibit distinct tendencies when examined as a function of the concentration and nature of the electrolyte. The behaviour of the observables changes drastically above 0.84M (NH4)2SO 4 and 0.60M NaCl. Static light scattering revealed a progressive restructuring of the fractals to compact structures at the latter stages of the reaction. Based on the correlations between the various observables an attempt is made to predict the long-term fate of the nucleating solutions.

Static and dynamic light scattering have been employed to investigate the behaviour of nucleating lysozyme solutions in the range between 0.34 and 3.08mM. Preselected concentrations of NaC1 and (NH4)2SO 4 have been used to screen the repulsive Coulombic interactions and trigger aggregation. Initially, massfractals undergoing diffusion limited-like aggregation coexist with monomers or small lysozyme oligomers. The growth kinetics of the fractals deliver observables that exhibit distinct tendencies when examined as a function of lysozyme concentration. The behaviour of the observables changes drastically around 2.0mM lysozyme. Static light scattering experiments revealed progressive restructuring or growth of compact structures at later stages of the aggregation. Based on the correlations between the observables an attempt is made to predict whether the examined solutions will crystallize or not. A tentative scheme, involving the most prominent structures observed in nucleating lysozyme solutions, is discussed.

A comparitive study of the nanostructure evolving during aggregation of hen-egg white lysozyme in supersaturated solution was carried out by dynamic light scattering ͑DLS͒ and scanning force microscopy ͑SFM͒. Lysozyme aggregate ͑cluster͒ formation was observed in solution in the presence of NaCl, ͑NH 4 ͒ 2 SO 4 , and NaNO 3 as precipitating agents. The growth kinetics were examined by DLS and revealed fractal growth of the clusters with a fractal dimension of 1.8 obtained independently of the type of inert salt. Such behavior is typical for diffusion-limited cluster-cluster ͑DLCA͒ aggregation. Initial lysozyme cluster sizes were in the range of 12-35 nm. SFM images of individual lysozyme clusters at the liquid-solid interface were obtained in the presence of NaCl and NaNO 3 under crystallization conditions, and revealed cluster sizes in agreement with those determined by DLS. Extended domains of smaller sized clusters appeared on the mica surface after subjecting supersaturated lysozyme solutions to a dialysis step. The feasibility of DLS and SFM for monitoring the nano-and mesoscopic morphology of lysozyme aggregates in supersatured solutions and at the solid-liquid interface is discussed.