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Titolo:
Nucleation of protein crystals: critical nuclei, phase behavior, and control pathways
Autore:
Galkin, O; Vekilov, PG;
Indirizzi:
Univ Alabama, Ctr Micrograv & Mat Res, Dept Chem, Huntsville, AL 35899 USAUniv Alabama Huntsville AL USA 35899 Dept Chem, Huntsville, AL 35899 USA
Titolo Testata:
JOURNAL OF CRYSTAL GROWTH
fascicolo: 1-4, volume: 232, anno: 2001,
pagine: 63 - 76
SICI:
0022-0248(200111)232:1-4<63:NOPCCN>2.0.ZU;2-V
Fonte:
ISI
Lingua:
ENG
Soggetto:
SUPERSATURATED LYSOZYME SOLUTIONS; HOMOGENEOUS NUCLEATION; DENSITY-FLUCTUATIONS; METASTABLE STATES; GLOBULAR-PROTEINS; CRYSTALLIZATION; SEPARATION; KINETICS; SOLUBILITY; GLYCEROL;
Keywords:
biocrystallization; nucleation; phase diagrams; phase equilibria; solubility; biological macromolecules;
Tipo documento:
Article
Natura:
Periodico
Settore Disciplinare:
Physical, Chemical & Earth Sciences
--discip_EC--
Citazioni:
78
Recensione:
Indirizzi per estratti:
Indirizzo: Vekilov, PG Univ Alabama, Ctr Micrograv & Mat Res, Dept Chem, Huntsville, AL 35899 USA Univ Alabama Huntsville AL USA 35899 Huntsville, AL 35899 USA
Citazione:
O. Galkin e P.G. Vekilov, "Nucleation of protein crystals: critical nuclei, phase behavior, and control pathways", J CRYST GR, 232(1-4), 2001, pp. 63-76

Abstract

We have studied the nucleation of crystals of the model protein lysozyme using a novel technique that allows direct determinations of homogeneous nucleation rates. At constant temperature of 12.6 degreesC we varied the thermodynamic supersaturation by changing the concentrations of protein and precipitant. We found a broken dependence of the homogeneous nucleation rate onsupersaturation that is beyond the predictions of the classical nucleationtheory. The nucleation theorem allows us to relate this to discrete changes of the size of the crystal nuclei with increasing supersaturation as (10 or 11) --> (4 or 5) --> (1 or 2). Furthermore, we observe that the existence of a second liquid phase at high protein concentrations strongly affects crystal nucleation kinetics. We show that the rate of homogeneous nucleation of lysozyme crystals passes through a maximum in the vicinity of the liquid-liquid phase boundary hidden below the liquidus (solubility) line in thephase diagram of the protein solution. We found that glycerol and polyethylene glycol (PEG), which do not specifically bind to proteins, shift this phase boundary and significantly suppress or enhance the crystal nucleation rates, although no simple correlation exists between the action of PEG on the phase diagram and the nucleation kinetics. This provides for a control mechanism which does not require changes in the protein concentration, or the acidity and ionicity of the solution. The effects of the two additives onthe phase diagram strongly depend on their concentration and this providesopportunities for further tuning of nucleation rates. (C) 2001 Elsevier Science B.V. All rights reserved.

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Documento generato il 26/09/20 alle ore 00:59:30