The Interface between a Protein Crystal and an Aqueous Solution and Its Effects on Nucleation and Crystal Growth

Haas, C.; Drenth, Jan

doi:10.1021/jp993210a

Cited by 58 publications

(69 citation statements)

References 70 publications

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“…6 even in the stable region the proximity of a¯uid±¯uid critical point may have a signi®cant effect on the dynamics owing to the appearance of critical¯uctuations, which may enhance crystal nucleation 63,64 . The nucleus can also be enveloped by a¯uid layerÐthis coating would alter the surface tension and thus the nucleation and growth process 65 . Within the metastable region the Ostwald rule implies that¯uid± uid phase separation would precede the¯uid±crystal transition.…”

Section: The Effect Of Metastable Statesmentioning

confidence: 99%

Insights into phase transition kinetics from colloid science

Anderson

Lekkerkerker

2002

Nature

910

845

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Colloids display intriguing transitions between gas, liquid, solid and liquid crystalline phases. Such phase transitions are ubiquitous in nature and have been studied for decades. However, the predictions of phase diagrams are not always realized; systems often become undercooled, supersaturated, or trapped in gel-like states. In many cases the end products strongly depend on the starting position in the phase diagram and discrepancies between predictions and actual observations are due to the intricacies of the dynamics of phase transitions. Colloid science aims to understand the underlying mechanisms of these transitions. Important advances have been made, for example, with new imaging techniques that allow direct observation of individual colloidal particles undergoing phase transitions, revealing some of the secrets of the complex pathways involved.F igure 1 illustrates three types of phase diagram. The ®rst (Fig. 1a) is a simple system of hard spheres. Introducing attractions results in three-phase equilibria, as in atomic systems such as argon (Fig. 1b). With shorter-range attractions the gas±liquid (or¯uid±¯uid) equilibrium becomes metastable (Fig. 1c). This is often observed in protein systems. One might assume equilibrium diagrams show the complete picture, with perhaps the initial distance from the phase boundary (indicative of the distance to equilibrium) controlling the speed with which the equilibrium phases are attained; however, this is the exception rather than the rule.Hard-sphere colloids suspended in a solvent provide an excellent illustration of the dif®culties involved in understanding the equilibrium states and the mechanisms by which systems evolve. Entropy considerations predict that these systems will form crystals if the volume fraction is increased. Above the`freezing' volume fraction, f f 0:494, it is entropically favourable if some spheres are in a crystal, but above the`melting' volume fraction, f m 0:545, all spheres should be in a crystal (Fig. 1a). However this is not always the situation found experimentally, either because the conditions the theory assumes (low polydispersity, for example) are not satis®ed, or the dynamics of the system have dictated a different structure (note that we cannot say that this structure is the equilibrium structureÐif entropy favours crystal formation then a crystal will form eventually, however the system may remain in the less-favoured state for a signi®cant amount of time). This crystallization process is often interpreted within the familiar framework of nucleation and growth. There has been renewed interest in this mechanism recently, both with simulations 1 and experimentally 2,3 : by monitoring the individual particles undergoing the transition it is possible to evaluate and improve the model.The classical theory predicts that the free energy cost, DG, of forming a nucleus of radius r is:where g is the surface free energy, r is the density of the bulk liquid, and Dm is the chemical potential difference between the bulk solid and bulk liquid...

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Section: The Effect Of Metastable Statesmentioning

confidence: 99%

Insights into phase transition kinetics from colloid science

Anderson

Lekkerkerker

2002

Nature

910

845

View full text Add to dashboard Cite

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“…This means that the nucleation of crystals in TSC is enhanced because of the presence of metastable amorphous dense droplets, consistent with the previous theoretical predictions. [8][9][10][11] One of the implications associated with the mononuclear mechanism is that all dense droplets can grow large enough to develop a crystal. However, a good deal of experimental evidence shows that, although many dense droplets were created initially, only a fraction of them could successfully produce a crystal.…”

Section: Introductionmentioning

confidence: 99%

Multistep Crystal Nucleation: A Kinetic Study Based on Colloidal Crystallization

Zhang

Liu

2007

J. Phys. Chem. B

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Crystallization via an amorphous precursor, the so-called multistep crystallization (MSC), plays a key role in biomineralization and protein crystallization. MSC has attracted much attention in the past decade, but a quantitative understanding of it has so far not been available. The major challenge is that the kinetics governing the nucleation of crystals occurring in the metastable amorphous precursor remains unclear. In this study, the kinetics of MSC is addressed experimentally. Most importantly, a mathematical method is developed to calculate the local nucleation rate of the crystals in the amorphous precursor, which is not accessible to conventional methods. This local nucleation rate is critical to the understanding of MSC, but it has never been dealt with experimentally because of the difficulties of in situ observation. With the local crystal nucleation rates, the supersaturation for crystallization and the crystal-liquid interfacial free energy in the amorphous precursor are evaluated.

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“…In a computer simulation study, it was found that the presence of a metastable fluid-fluid critical point drastically changes the pathway for the formation of a critical nucleus and the large density fluctuations near the critical point increase the nucleation rate [8]. Haas and Drenth discuss the nucleation mechanisms in the liquid-liquid phase separation zone [9] and attempt a theoretical explanation for enhanced nucleation rates. Liquid-liquid spinodal decomposition followed by nucleation was proposed by Georgalis et al [10].…”

Section: Introductionmentioning

confidence: 99%

Dependence of nucleation kinetics and crystal morphology of a model protein system on ionic strength

Bhamidi

Skrzypczak‐Jankun

Schall

2001

Journal of Crystal Growth

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Nucleation rate data for hen egg-white lysozyme crystallization were obtained using a particle counter. Tetragonal lysozyme crystals were expected to form at the temperature and solution conditions of these experiments: 48C, pH 4.5 with 0.1 M sodium acetate buffer and 2-6% NaCl (w/v). The rates varied as expected, as smooth monotonic functions of supersaturation at 2%, 3% and 6% NaCl. However, at 5% NaCl, a great deal of scatter in the data was observed. At 2% and 3% NaCl, all the batches contained crystals with tetragonal morphology. At 6% NaCl, almost all of the vials contained the white powder with few or no tetragonal crystals. At 5% NaCl concentration, a mixture of tetragonal crystals and powder formed in varying proportions in all the vials as observed by visual inspection. The powdery material was examined using optical microscopy and was seen to consist of needles with regular structure and sharp, faceted edges. Powder diffraction data from these needles was inconsistent with experimental powder diffraction data from tetragonal lysozyme crystals. It is possible that at high salt and protein concentrations liquid-liquid separation occurred and yielded a crystal polymorph. #

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The Interface between a Protein Crystal and an Aqueous Solution and Its Effects on Nucleation and Crystal Growth

Cited by 58 publications

References 70 publications

Insights into phase transition kinetics from colloid science

Insights into phase transition kinetics from colloid science

Multistep Crystal Nucleation: A Kinetic Study Based on Colloidal Crystallization

Dependence of nucleation kinetics and crystal morphology of a model protein system on ionic strength

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