Figure 4.

Schematic of the set-up for crystallization experiments with FID (a,b) and FID centrifugation (c). (a) Experimental set-up in which the protein solution is carefully layered on top of the precipitant solution, where only few crystals form at the interface. (b) In the inverse set-up the precipitant solution is added dropwise to the protein solution, inducing increased transient nucleation at the drop–protein interface. (c) The experiment shown in (b) is continued by centrifugation. The nuclei formed in the protein solution are accelerated by centrifugation towards the interface zone, where they grow into nano- or microcrystals. When they reach a specific size they sediment into the precipitant zone, where they stop growing. Thereby nano- or microcrystals with a very narrow size distribution can be achieved.