Carbon-Nanotube-Based Materials for Protein Crystallization

Asanithi, Piyapong; Saridakis, Emmanuel; Govada, Lata; Jurewicz, Izabela; Brunner, Eric W.; Ponnusamy, Rajesh; Cleaver, J.A.S.; Dalton, Alan B.; Chayen, Naomi E.; Sear, Richard P.

doi:10.1021/am9000858

Cited by 61 publications

(87 citation statements)

References 29 publications

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“…The metastable conditions for heterogeneous crystallization of proteins reported in the literature were used as the starting point in the current work 2,16,34 . To isolate the influence of the surface porosity on …”

Section: Effect Of Nucleant Surface Porosity On Protein Crystallizationmentioning

confidence: 99%

Selective Crystallization of Proteins Using Engineered Nanonucleants

Shah

Williams

Heng

2012

Crystal Growth & Design

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Abstract:This study reports for the first time a detailed experimental investigation of protein crystallization in engineered nano-confined spaces with both controlled pore diameters and narrow pore size distributions. We propose a systematic approach for controlling the nucleation and crystallization of biological macromolecules based on a relationship between the protein radius of gyration (R g ) and specific pore diameter. A series of nano-nucleants with ordered mesopores having narrow pore size distributions were prepared. The templates were tested for proteins ranging in molecular weight from 14kDa to 450kDa. Well formed protein crystals were obtained on only one of the five presented nanonucleants for all protein cases tested, highlighting the unique template selectivity exhibited by these nucleants. In addition, Concanavalin A and Catalase were both crystallized at ∼2 times lower supersaturation levels than previously reported by any known method. Our observations fully support theoretical studies which predict the enhanced thermodynamic stability of proteins in nanoconfined cavities, including specifically the importance of nucleant pore diameter with respect to protein radius of gyration. The nucleants described here could have major industrial applications for downstream separation and purification of biopharmaceuticals, as well as improved opportunities for the crystallization of complex proteins for structural determination.

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Section: Effect Of Nucleant Surface Porosity On Protein Crystallizationmentioning

confidence: 99%

Selective Crystallization of Proteins Using Engineered Nanonucleants

Shah

Williams

Heng

2012

Crystal Growth & Design

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“…Adsorption or immobilization of proteins and peptides on solid substrates plays an important role in many biotechnological applications, such as biocatalysis, biosensing, biomaterials, surface-induced protein crystallization, and drug delivery systems [1][2][3][4][5][6][7][8][9][10]. As a matter of fact, the success of these applications strongly depends on the activities of the adsorbed proteins and peptides which are determined by their conformations on substrates.…”

Section: Introductionmentioning

confidence: 99%

Effects of surface hydrophobicity on the conformational changes of polypeptides of different length

Yan

2011

Phys. Rev. E

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We studied the effects of surface hydrophobicity on the conformational changes of different length polypeptides by calculating the free energy difference between peptide structures using the bias-potential Monte Carlo technique and the probability ratio method. It was found that the hydrophobic surface plays an important role in the stability of secondary structures of the polypeptides with hydrophobic side chains. For short GAAAAG peptides, the hydrophobic surface destabilizes the α helix but stabilizes the β hairpin in the entire temperature region considered in our study. Interestingly, when the surface hydrophobic strength ε(hpsf)≥ε(hp), the most stable structure in the low temperature region changes from α helix to β hairpin, and the corresponding phase transition temperature increases slightly. For longer GAAAAAAAAAAG peptides, the effects of the relatively weak hydrophobic surface (ε(hpsf) < ε(hp)) on α-helical structures may be neglected, while the relatively strongly hydrophobic surface (ε(hpsf)≥ε(hp)) leads to the obvious partial helicity loss. In contrast, the stability of β structures can be enhanced significantly by the hydrophobic surface, especially by the strongly hydrophobic surface, at low and intermediate temperatures. At high temperatures, in addition to thermal fluctuations, the strongly hydrophobic surface (ε(hpsf)>ε(hp)) may further disturb the formation of both α-helical and β structures. Moreover, the phase transition temperature between α-helical structures and random coils significantly decreases due to the helicity loss when ε(hpsf)>ε(hp). Our findings provide a basic and quantitative picture for understanding the effects of a hydrophobic surface on the conformational changes of the polypeptides with hydrophobic side chains. From an application viewpoint, the present study is helpful in developing alternative strategies of producing high-quality biological fibrillar materials and functional nanoscale devices by the self-assembly of the polypeptides on hydrophobic surfaces.

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“…An alternative to templates was pioneered by Chayen and co-workers [2][3][4], who showed that materials with disordered nanoscale pitted surfaces can act as ''universal'' nucleation agents in the sense that they induce the nucleation of crystals of many different proteins. See Refs.…”

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confidence: 99%

Design Principles for Broad-Spectrum Protein-Crystal Nucleants with Nanoscale Pits

2010

Self Cite

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Growing high-quality crystals is a bottleneck in the determination of protein structures by x-ray diffraction. Experiments find that materials with a disordered pitted surface seed the growth of protein crystals. Here we report computer simulations of rapid crystal nucleation in nanoscale pits. Nucleation is rapid, as the crystal forms in pits that have filled with liquid via capillary condensation. Surprisingly, we find that pits whose surfaces are rough are better than pits with crystalline surfaces; the roughness prevents the growing crystal from trying to conform to the pit surface and becoming strained. DOI: 10.1103/PhysRevLett.105.205501 PACS numbers: 81.10.Aj, 64.60.QÀ, 64.70.dg, 87.15.nt The faster crystals grow, the more defects they contain. Hence, high-quality protein crystals that can be used in xray or neutron diffraction studies are ideally grown at low supersaturation where crystal growth is slow. Yet, to nucleate a protein crystal from solution, the supersaturation cannot be too small, because then crystals never form as nucleation is effectively suppressed. The challenge for protein crystallization is therefore to nucleate crystals at supersaturations that are so low that crystal growth is slow. One possible strategy to achieve this objective is to make use of heterogeneous nucleation: a suitable nucleation agent can induce crystallization under conditions where homogeneous (bulk) crystal nucleation is negligible and crystal growth is slow. The design of suitable crystalnucleating agents is therefore of great practical importance.The rational design of such agents is hampered by a lack of understanding of the molecular mechanism of nucleation. One might think that the best strategy is to use structured templates that match the lattice spacing of the target crystal. Indeed, experiments on colloidal systems have shown that a template with a periodic surface pattern can strongly enhance crystal growth via epitaxy [1]. However, unless there is a precise match between the lattice spacing of the template and that of the epitaxially grown crystal, epitaxial crystal growth is not possible. Thus templates tend to work only for specific target crystals that are commensurate with the periodicity of the template. Such highly specific templates are of little use if we want to crystallize a wide variety of proteins with different and a priori unknown crystal lattices.An alternative to templates was pioneered by Chayen and co-workers [2-4], who showed that materials with disordered nanoscale pitted surfaces can act as ''universal'' nucleation agents in the sense that they induce the nucleation of crystals of many different proteins. See Refs. [5,6] for reviews of protein crystallization.In this Letter we present Monte Carlo simulations that investigate the mechanism of protein crystallization in nanoscale pits. Our aim is to study heterogeneous crystal nucleation in a simple model system with a phase diagram similar to that of many globular-protein solutions, such as lysozyme. Our computer simulations reve...

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Carbon-Nanotube-Based Materials for Protein Crystallization

Cited by 61 publications

References 29 publications

Selective Crystallization of Proteins Using Engineered Nanonucleants

Selective Crystallization of Proteins Using Engineered Nanonucleants

Effects of surface hydrophobicity on the conformational changes of polypeptides of different length

Design Principles for Broad-Spectrum Protein-Crystal Nucleants with Nanoscale Pits

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