Time-Resolved Small-Angle Static Light Scattering on Lysozyme during Nucleation and Growth

Abstract

Hen egg white lysozyme was employed for studying aggregation and nucleation events induced by simple electrolytes such as NaCl while the process was monitored by time-resolved, small-angle static light scattering. The fractal dimension, the weight-average molecular weight, the mean radius of gyration and the homogeneity exponent, which typify cluster reactivity, were determined as a function of the elapse reaction time. The observed clusters resemble mass-fractals; however, direct classification to the limiting diffusion or reaction aggregation regimes is 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 behavior of dimensionalities and exponents is observed when the latter are plotted as a function of lysozyme or electrolyte concentration. The implications of fractal structure formation during the nucleation of lysozyme are discussed.

Rheopexy of synovial fluid and protein aggregation

“…This viscoelastic character is also consistent with the notion of BSA aggregation (non-aggregated 11 mg ml K1 BSA solutions would be expected to be Newtonian in this range of shear rates). Such shear thinning character has been reported for a variety of globular protein aqueous solutions (Tung 1978;Inoue & Matsumoto 1994;Matsumoto & Inoue 1996;Ikeda & Nishinari 2000, 2001a. Application of strong shear, ultrasonic treatment and sterile filtering of the albumin solutions did not qualitatively change the observed viscoelastic character of the BSA solutions, reflected in either the apparent shear thinning or the rheopexy (Oates 2002).…”

Solvent-induced lysozyme gels: Rheology, fractal analysis, and sol–gel kinetics

“…Fractals have been described for lysozyme aggregates, obtained upon salt addition in aqueous buffered solution, through quasi-elastic light scattering [24,25]. On the time scale considered, a rigid internal structure of the aggregates was verified, which has been claimed by the authors [24] as a possible form of reconciling their fractal structure with their colloid-like ordering [26].…”

Aggregation Kinetics of Metal Chalcogenide Nanocrystals: Generation of Transparent CdSe (ZnS) Core (Shell) Gels

“…Fast, diffusion-limited colloidal aggregation (DLCA), in which growth of the average cluster size has a power law behavior; and slow, reaction-limited colloidal aggregation (RLCA), in which exponential growth of the average cluster size occurs. 13 In the DLCA regime, power law behavior of the growth in the average radius of gyration R̄ g of the aggregates can be shown by solution of the Smoluchowski equation (Equation 7) 14 …”