Fast and simple purification of histidine‐tagged proteins using His GraviTrap

Carlsson, Marianne; Bergh, A. A. Hijmans van den; Karlsson, Anneli; Lindgren, Helena

doi:10.1096/fasebj.20.4.a102-b

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“…Surface Complexation Modeling. The computer program, Solgaswater, 22,23 was used to model speciation and surface complexation. Because we do not have access to spectroscopic data that would indicate the coordination mode of the organic ligands, we cannot justify the inclusion of additional parameters that would be required for modeling outer sphere complexation or adsorption in a multisite model (CD-MUSIC model by Wolthers 2008 24 ).…”

Section: ■ Materials and Methodsmentioning

confidence: 99%

Biomineralization: Long-Term Effectiveness of Polysaccharides on the Growth and Dissolution of Calcite

Sand

Pedersen²,

Sjöberg

et al. 2014

Crystal Growth & Design

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Our results demonstrate that in addition to being used for controlling morphology during calcite growth, polysaccharide (PS) that has been designed for biomineralization is also extremely robust, influencing calcite reactions even after millions of years. We investigated calcite (CaCO 3 ) behavior in solutions with very small concentrations of PS that was produced ∼70 Ma ago by coccolithophorids. We used atomic force microscopy (AFM) and the constant composition method to monitor calcite growth in the presence of this ancient PS. The ancient PS is still very active and has a high affinity for calcite step edges. Adsorption, even at extremely low concentrations (0.5 μg/mL), results in decreased growth rate and dramatic morphology changes during growth and dissolution. The experimental results are complemented with surface complexation modeling for adsorption of components of polysaccharide from a modern coccolithophorid, Emiliania huxleyi. We generated surface complexation constants for the branch components: malonate: 14.25 ± 0.17, succinate: 11.91 ± 0.06, tricarballylate: 14.86 ± 0.04, and citrate: 15.25 ± 0.04. The implication is that complex PS could hold promise for smart material engineering and for preventing scaling. ■ INTRODUCTIONControl on crystal growth, such as is imposed by polysaccharides (PS) produced by coccolithophorids, is of fundamental interest for understanding biomineralization. Also, once the mechanisms of how organisms create minerals and control growth are understood, implications will range to include new paths for smart material engineering and industry spin-off applications. Several studies have addressed PS−calcite interactions to investigate how algal species manage to produce their complex external spheres of calcite shields. For example, the calcite interaction with coccolith associated polysaccharide extracted from recent coccoliths, e.g., Emiliania huxleyi 1−7 and several model acidic PS have been investigated, e.g., refs 3, 5, and 8−10, showing that acidic PS influence calcite formation, growth, and recrystallization. 11 Here, we report on the robustness and effectiveness of PS that were produced by single celled algae ∼70 million years ago. We have examined the adsorption behavior of the ancient PS and its effect on the growth and dissolution of calcite.The ancient PS was extracted from chalk deposited during the Maastrichtian (70−65 Ma) and collected as drill cores from the North Sea Basin. Many of the grains in this, and many other, chalk deposits still outline the coccoliths once deposited, and the biogenic material from the chalk has been suggested to have prevented recrystallization due to Ostwald ripening. 12,13 Pedersen et al. 14 found that the extracted ancient PS contain ∼40% acidic monosaccharides and more than 20% mannose. The presence of mannose is consistent with a mannose backbone, similar to that reported for coccolith associated PS (CAP) extracted from cultures of the modern coccolithophore E. huxleyi. 2 We have considered the E. huxleyi PS as the modern analogue...

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Section: ■ Materials and Methodsmentioning

confidence: 99%