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Peter G Vekilov - One of the best experts on this subject based on the ideXlab platform.

  • Nucleation of Protein Crystals: Critical Nuclei, Phase Behavior, and Control Pathways
    Journal of Crystal Growth, 2001
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    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°C we varied the thermodynamic supersaturation by changing the concentrations of protein and precipitant. We found a broken dependence of the homogeneous nucleation rate on supersaturation that is beyond the predictions of the classical nucleation theory. 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 the phase 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 on the phase diagram strongly depend on their concentration and this provides opportunities for further tuning of nucleation rates.

  • control of protein crystal nucleation around the metastable liquid liquid phase boundary
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    The capability to enhance or suppress the nucleation of protein crystals opens opportunities in various fundamental and applied areas, including protein crystallography, production of protein crystalLine pharmaceuticals, protein separation, and treatment of protein condensation diseases. Herein, 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 the phase diagram of the protein solution. We found that glycerol and polyethylene glycol (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 polyethylene glycol on the phase diagram and the nucleation kinetics. The control mechanism does not require changes in the protein concentration, acidity, and ionicity of the solution. The effects of the two additives on the phase diagram strongly depend on their concentration, which provides opportunities for further tuning of nucleation rates.

  • Control of protein crystal nucleation around the metastable liquid–liquid phase boundary
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    The capability to enhance or suppress the nucleation of protein crystals opens opportunities in various fundamental and applied areas, including protein crystallography, production of protein crystalLine pharmaceuticals, protein separation, and treatment of protein condensation diseases. Herein, 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 the phase diagram of the protein solution. We found that glycerol and polyethylene glycol (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 polyethylene glycol on the phase diagram and the nucleation kinetics. The control mechanism does not require changes in the protein concentration, acidity, and ionicity of the solution. The effects of the two additives on the phase diagram strongly depend on their concentration, which provides opportunities for further tuning of nucleation rates.

Oleg Galkin - One of the best experts on this subject based on the ideXlab platform.

  • Nucleation of Protein Crystals: Critical Nuclei, Phase Behavior, and Control Pathways
    Journal of Crystal Growth, 2001
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    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°C we varied the thermodynamic supersaturation by changing the concentrations of protein and precipitant. We found a broken dependence of the homogeneous nucleation rate on supersaturation that is beyond the predictions of the classical nucleation theory. 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 the phase 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 on the phase diagram strongly depend on their concentration and this provides opportunities for further tuning of nucleation rates.

  • control of protein crystal nucleation around the metastable liquid liquid phase boundary
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    The capability to enhance or suppress the nucleation of protein crystals opens opportunities in various fundamental and applied areas, including protein crystallography, production of protein crystalLine pharmaceuticals, protein separation, and treatment of protein condensation diseases. Herein, 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 the phase diagram of the protein solution. We found that glycerol and polyethylene glycol (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 polyethylene glycol on the phase diagram and the nucleation kinetics. The control mechanism does not require changes in the protein concentration, acidity, and ionicity of the solution. The effects of the two additives on the phase diagram strongly depend on their concentration, which provides opportunities for further tuning of nucleation rates.

  • Control of protein crystal nucleation around the metastable liquid–liquid phase boundary
    Proceedings of the National Academy of Sciences of the United States of America, 2000
    Co-Authors: Oleg Galkin, Peter G Vekilov
    Abstract:

    The capability to enhance or suppress the nucleation of protein crystals opens opportunities in various fundamental and applied areas, including protein crystallography, production of protein crystalLine pharmaceuticals, protein separation, and treatment of protein condensation diseases. Herein, 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 the phase diagram of the protein solution. We found that glycerol and polyethylene glycol (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 polyethylene glycol on the phase diagram and the nucleation kinetics. The control mechanism does not require changes in the protein concentration, acidity, and ionicity of the solution. The effects of the two additives on the phase diagram strongly depend on their concentration, which provides opportunities for further tuning of nucleation rates.

Ying Wang - One of the best experts on this subject based on the ideXlab platform.

  • Metastability Gap in the Phase Diagram of Monoclonal IgG Antibody
    Biophysical journal, 2017
    Co-Authors: Jacob B. Rowe, Rachel A. Cancel, Tyler D. Evangelous, Rhiannon P. Flynn, Sergei Pechenov, J. Anand Subramony, Jifeng Zhang, Ying Wang
    Abstract:

    Abstract Crystallization of IgG antibodies has important applications in the fields of structural biology, biotechnology, and biopharmaceutics. However, a rational approach to crystallize antibodies is still lacking. In this work, we report a method to estimate the Solubility of antibodies at various temperatures. We experimentally determined the full phase diagram of an IgG antibody. Using the full diagram, we examined the metastability gaps, i.e., the distance between the crystal Solubility Line and the liquid-liquid coexistence curve, of IgG antibodies. By comparing our results to the partial phase diagrams of other IgGs reported in literature, we found that IgG antibodies have similar metastability gaps. Thereby, we present an equation with two phenomenological parameters to predict the approximate location of the Solubility Line of IgG antibodies with respect to their liquid-liquid coexistence curves. We have previously shown that the coexistence curve of an antibody solution can be readily determined by the polyethylene glycol-induced liquid-liquid phase separation method. Combining the polyethylene glycol-induced liquid-liquid phase separation measurements and the phenomenological equation in this article, we provide a general and practical means to predict the thermodynamic conditions for crystallizing IgG antibodies in the solution environments of interest.

Vera B. Henriques - One of the best experts on this subject based on the ideXlab platform.

  • Phase diagram of dilute lattice surfactant solution
    The Journal of Chemical Physics, 2001
    Co-Authors: Cláudio S. Shida, Vera B. Henriques
    Abstract:

    We have studied the temperature–composition phase diagram for a dilute surfactant model solution on the square lattice through Monte Carlo simulations. A micellar region and a Solubility Line were identified from the measurement of different properties, among which the volume fraction of aggregate, specific heat, and convergence of relaxation from different initial conditions. We have compared properties of the above system with those of a symmetric lattice solution in the dilute regime. Comparison of data allow an interpretation of the micellar phase as a transition region between a microscopically homogeneous phase and a solid phase.

Juergen Hubbuch - One of the best experts on this subject based on the ideXlab platform.

  • From osmotic second virial coefficient (B22 ) to phase behavior of a monoclonal antibody.
    Biotechnology progress, 2015
    Co-Authors: Natalie Rakel, Katharina Christin Bauer, Lara Galm, Juergen Hubbuch
    Abstract:

    Antibodies are complex macromolecules and their phase behavior as well as interactions within different solvents and precipitants are still not understood. To shed some light into the processes on a molecular dimension, the occurring self-interactions between antibody molecules were analyzed by means of the osmotic second virial coefficient (B22). The determined B22 follows qualitatively the phenomenological Hofmeister series describing the aggregation probability of antibodies for the various solvent compositions. However, a direct correlation between crystallization probability and B22 in form of a crystallization slot does not seem to be feasible for antibodies since the phase behavior is strongly dependent on their anisotropy. Kinetic parameters have to be taken into account due to the molecular size and complexity of the molecules. This is confirmed by a comparison of experimental data with a theoretical phase diagram. On the other hand the Solubility is thermodynamically driven and therefore the B22 could be used to establish a universal Solubility Line for the monoclonal antibody mAb04c and different solvent compositions by using thermodynamic models. © 2015 American Institute of Chemical Engineers Biotechnol. Prog., 31:438–451, 2015