Publication Details
Overview
 
 
Sander Stroobants, Yuchen Zhang, Marco A C Potenza, Peter Vekilov, Johan Stiens, Dominique Maes
 

Unpublished contribution to conference

Abstract 

Protein crystallization is still an elusive process, consisting of two steps. In the first step a nucleus is formed, followed by growth of this nucleus into a crystal. The inherent stochastic nature of nucleation makes it difficult to predict when and where a critical nucleus will appear. Moreover, the small size of the nucleus prohibits direct observation.Theoretical predictions based on the classical nucleation theory (CNT) can be orders of magnitude different than experimental observations. To explain this discrepancy new theories have been developed. One of these new developments is two step nucleation (TSN). TSN assumes that dense liquid protein clusters that form inside the crystallization solution will act as nucleation sites. Nucleation underlies aggregation processes observed in diseases such as Alzheimer and cataract. Nucleation also determines the characteristics of the resulting crystal.In order to challenge these theories, we investigate the potential of novel techniques to detect nucleation and to characterize the pre nucleation clusters:• Brownian microscopy is able to visualize the speckle pattern of the metastable liquid clusters. The speckle pattern contains information about the size and the dynamics of the observed particles.• THz waves have been shown to probe the dynamics of the water molecules, specifically the water in the hydration shell around the protein. Detecting changes in the properties of the hydration water allows us to detect the formation of clusters and crystals in an earlier stage than currently possible,.• Confocal Depolarized Dynamic Light Scattering (CDDLS) intensity scales with the anisotropy of the particle, providing information about the crystallinity of the observed particles. As such this is the only technique that can distinguish between dense liquid clusters and crystalline nuclei.Results of this novel technique will be compared with established and less performant techniques: for example, Dynamic Light Scattering (DLS) and turbidity measurements.

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