TIME-RESOLVED SMALL-ANGLE STATIC LIGHT-SCATTERING ON LYSOZYME DURING NUCLEATION AND GROWTH

Hen egg white lysozyme was employed for studying aggregation and nucle ation events induced by simple electrolytes such as NaCl while the pro cess was monitored by time-resolved, small-angle static light scatteri ng. The fractal dimension, the weight-average molecular weight, the me an radius of gyration and the homogeneity exponent, which typify clust er reactivity, were determined as a function of the elapse reaction ti me. The observed clusters resemble mass-fractals; however, direct clas sification to the limiting diffusion or reaction aggregation regimes i s not straightforward and the findings verify deviations postulated in previous works. In nucleating solutions the interplay between packing and electrostatics makes the situation more complex than anticipated so far. A delicate balance exists between the conditions that optimize charge screening and those promoting gel formation. A nonmonotonic be havior of dimensionalities and exponents is observed when the latter a re plotted as a function of lysozyme or electrolyte concentration. The implications of fractal structure formation during the nucleation of lysozyme are discussed.