LYSOZYME AGGREGATION STUDIED BY LIGHT-SCATTERING .2. VARIATIONS OF PROTEIN-CONCENTRATION

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 NaCl and (NH4)(2)SO4 have been used to screen the repulsive Coulombic interactions and trigger aggregation. Initially, mass-fractals undergoing diffusion limited-lik e aggregation coexist with monomers or small lysozyme oligomers. The g rowth kinetics of the fractals deliver observables that exhibit distin ct tendencies when examined as a function of lysozyme concentration. T he behaviour of the observables changes drastically around 2.0mM lysoz yme. Static light scattering experiments revealed progressive restruct uring or growth of compact structures at later stages of the aggregati on. Based on the correlations between the observables an attempt is ma de to predict whether the examined solutions will crystallize or not. A tentative scheme, involving the most prominent structures observed i n nucleating lysozyme solutions, is discussed.