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| Home > Publications database > Change of Fractal Dimension during the early stages ofLysozyme Crystallization |
| Home > Publications database > Change of Fractal Dimension during the early stages ofLysozyme Crystallization |
| Poster | FZJ-2015-06972 |
; ; ; ; ;
2015
Please use a persistent id in citations: http://hdl.handle.net/2128/9504
Abstract: In this study we focussed on the question of how to grow crystals as large as possible in light of their use as samples for neutron protein crystallography. We concentrated on the early stages of the crystallization process where the directions are set whether many small crystals grow or few large ones. We used lysozyme as a model system since it has been studied well in the past and the phase diagram of its crystal growth is known. In order to study the crystal growth process starting from the very beginning we used a combination of three scattering techniques since the involved size ranges require a large q-range. Small angle neutron scattering was used in combination with static light scattering on the same sample in order to realize this extended q-range and in order to obtain structural information on the growing crystal seeds. In situ dynamic light scattering at the neutron scattering sample cell was used to obtain an overview of all sizes present in the crystallisation process. The small angle neutron scattering technique required a crystallisation in heavy water instead of normal water. We found that the crystallization conditions did not differ too much from the ones mentioned in the literature for light water when using a corrected pD value of pD=pH+0.4. The crystallization is initiated by mixing a 60 mg/ml Lysozyme solution with a 6wt% NaCl acetate buffer solution (both at pD=4.75 and at 298 K) in a 1 :1 ratio. Immediately after mixing, dimers of lysozyme molecules are formed and the structure factor seen in the lysozyme stock solution disappears. Under the chosen conditions we could observe a fractal growth of the crystal seeds with a change of the fractal dimension from 1.0 to 1.7 in the first 90 min. This can be interpreted as a branched crystal seed being formed first which grows more in a linear manner with little branching. Later, the space in between the branched arms is filled to cross over to a more densely packed fractal. With these results theoretical models of crystal growth can be improved. Furthermore, the early detection of crystal seeds can be used to rapidly change the crystallization conditions (e. g. temperature) in order to avoid the production of more crystal seeds.
Keyword(s): Health and Life (1st) ; Health and Life (1st) ; Biology (2nd)
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