Elsevier

Journal of Membrane Science

Volume 545, 1 January 2018, Pages 229-239
Journal of Membrane Science

Preparation of Amphotericin B-Ergosterol structures and molecular simulation of water adsorption and diffusion

https://doi.org/10.1016/j.memsci.2017.09.032Get rights and content

Highlights

  • Amphotericin B-Ergosterol had the high potential as artificial water channels.

  • The hydrophobic central section provided rapid water molecule transport.

  • Both single- and double-layer channel simulations predicted high water permeability.

Abstract

In this study, molecular simulation was used to explore the structural characteristics and water transport performance of Amphotericin B-Brgosterol (AmBEr) channels. A molecular dynamics (MD) technique was used to construct two types of molecular models of AmBEr channels: single-layer channel (SLC) and double-layer channel (DLC). A MD simulation was used to illustrate the differences between SLC and DLC AmBEr models with respect to structure, channel diameter, interior affinity, and transportation behavior of water molecules. A Monte Carlo (MC) method was adopted to investigate the sorption behavior in these two types of AmBEr channels. The intramolecular properties and intermolecular interactions indicated the feasibility of the simple model construction method adopted in this study. The internal diameter and channel shape showed that the use of funnel-type AmBEr channels would lead to high levels of permeability and selectivity. The special tunnel shape was reflected in the diffusion calculation that resulted in a high displacement of water molecules in two types of channel models. The water molecule-channel hydrogen bond distribution and snapshot analyses of the adsorption site revealed an affinity between the amphotericin B monomer and water molecules. The novel chemical structure of the amphotericin B monomer features simultaneous hydrophilic and hydrophobic segments. This particular structural characteristic was reflected in the unique shape of the water adsorption isotherm curves, which show a unique three-step increase in equilibrated water pressure. In transport prediction, two AmBEr models had similar permeability values but different water transport mechanisms. Concisely, fabrication of the artificial water channel would help to enhance the water permeability in the water transport process. The results from the simulation provided valuable information for structural characterization and in estimating the transport behavior of the molecules in the AmBEr channels.

Introduction

Membrane technology has been widely applied to water treatment, because it is highly effective and economic for the separation of solvents or particulates from water [1]. For instance, the membrane process is used in reverse osmosis (RO) to achieve water desalination and purification [2], [3]. As the human population increases, the amount of required and supplied water that utilizes membrane processing will continue to increase. Due to the increased requirement for water, the search for higher performance membranes for separation processes will result in ever-increasing interest among scientists.

Biomimetic materials have been intensively studied for modification of their properties to enhance separation performance [4], [5], [6], [7], [8]. In order to obtain improved water mobility, Kumar et al. introduced the idea of embedding the properties of aquaporin into membranes that show exceptional water permeability [9]. Aquaporin is a type of protein channel that was discovered in 2003 by Peter Agre [10]. Aquaporin is a porous protein that resides on cell membranes to function as a selective “water channel,” and is expected to be applied to high-performance water treatment processes. The techniques involved in these structural transport properties have been widely studied in experimentation [11], [12], [13], [14], [15] and simulation [16], [17], [18], [19], [20]. However, aquaporin is very expensive and difficult to produce on a large scale. Therefore, artificial water channels using biomimetic materials have been widely studied and applied to water treatment membranes.

In recent decades, many specific materials have been considered as candidates for use as artificial water channels. For example, the structural properties and membrane performance of carbon nanotube (CNT) composite membranes were introduced in previous studies [21], [22], [23], [24]. Cyclic peptide nanotubes (CPNTs) have been designed for insertion into biological processes, and their specific nanostructures have revealed a high level of biocompatibility properties [25], [26], [27]. Gramicidin A (GA) is an ion-selective channel that can be inserted into a lipid bilayer, and it has shown water permeability that is comparable to aquaporin [28], [29], [30], [31], [32]. Besides the experimental research, theoretical study on a microscopic scale is considered a favorable method for exploring the characteristics of novel materials. Many simulation studies have investigated artificial water channels. As shown below, the mechanical and transport properties of carbon nanotubes have been explored via theoretical study [33], [34], [35], [36], [37]. The Gramicidin A channel model has been studied via molecular mechanics, dynamics simulation, and Monte Carlo technique [38], [39], [40], [41], [42]. Some theoretical studies have also been introduced to reveal the properties of cyclic peptide and their potential in biomaterials [43], [44], [45], [46], [47], [48]. The above studies have provided much useful information and have shown great agreement with the experimental data, which proves that molecular simulation is feasible as a method to design and analyze novel artificial water channels.

In this study, two models of Amphotericin B-Ergosterol (AmBEr) channels, single-layer channel (SLC) and double-layer channel (DLC), were constructed and explored. First, intermolecular and intramolecular properties were simulated via MD techniques. Second, simulated hydrogen bonds and adsorption site snapshots were analyzed to reflect the affinity between water molecules and channel surfaces. Finally, MD techniques were used to explore water diffusion, and Monte Carlo (MC) simulation was introduced to study water sorption behaviors. All these analytical tools were used to study SLC and DLC AmBEr models in this work. Simulated permeability can be calculated via the values of diffusivity and solubility. Thus, the simulated permeabilities of different models can be compared to understand the transport mechanisms. Further, from previous studies, Amphotericin B was proved that it can enhance water transport performance in membrane separation processes [49], [50], [51], [52]. Therefore, this kind of artificial water channel had a high potential for designing next generation biomimetic membranes.

In short, the objective of this work was to use molecular simulation to evaluate the difference in structural properties and compare the performances of SLC and DLC AmBEr simulation models. The results showed similar structural characteristics but indicated slightly different transport mechanisms. The details are discussed in the following sections.

Section snippets

Simulation method

This study was focused on an Amphotericin B-Ergosterol (AmBEr) channel model, and included the construction, structures, adsorption, and transport behaviors of water molecules. The difference between the two forms of the AmBEr model, SLC and DLC, was also explored in this work. In order to analyze the characteristics of the AmBEr channel, both simulation models were created using the MD simulation procedure. Furthermore, three essential features of this work, channel structure, sorption and

Model validation

To confirm the feasibility of all the molecular models in this work, some specific properties of the two types of channel models (SLC and DLC) were explored. These properties are helpful in validating the correctness and applicability of the simulation. Both SLC and DLC AmBEr models were constructed for validation before further exploration. The equilibrated structures of these two models of channels were achieved using MD simulation and NVT ensemble calculation. Simulation research that

Conclusion

The structural characteristics and transport behaviors of the two types of AmBEr channel models were thoroughly analyzed via MD and MC simulations. The intramolecular properties of the amphotericin B subunits and the intermolecular interaction between amphotericin B and ergosterol monomers were explored for model validation. The results illustrated the feasibility of the model construction method and validate the simulation model in this study. The channel morphology and calculated internal

References (62)

  • E. Celik et al.

    Carbon nanotube blended polyethersulfone membranes for fouling control in water treatment

    Water Res.

    (2011)
  • J.-H. Choi et al.

    Fabrication and characterization of multi-walled carbon nanotubes/polymer blend membranes

    J. Membr. Sci.

    (2006)
  • W.S. Horne et al.

    Antiviral cyclic d, l-α-peptides: targeting a general biochemical pathway in virus infections

    Bioorg. Med. Chem.

    (2005)
  • M.Ø. Jensen et al.

    Single-channel water permeabilities of Escherichia coli aquaporins AqpZ and GlpF

    Biophys. J.

    (2006)
  • B. Wallace

    Structure of gramicidin A

    Biophys. J.

    (1986)
  • K. Kim et al.

    Interaction of K+ ion with the solvated gramicidin A transmembrane channel

    Biophys. J.

    (1985)
  • W. Lee et al.

    Molecular dynamics simulation of cation motion in water-filled gramicidinlike pores

    Biophys. J.

    (1984)
  • D. Mackay et al.

    Structure and dynamics of ion transport through gramicidin A

    Biophys. J.

    (1984)
  • A. Skerra et al.

    Structure and dynamics of one-dimensional ionic solutions in biological transmembrane channels

    Biophys. J.

    (1987)
  • A. Skerra et al.

    Simulation of voltage-driven hydrated cation transport through narrow transmembrane channels

    Biophys. J.

    (1987)
  • H.-C. Wu et al.

    Preparation of cyclic peptide nanotube structures and molecular simulation of water adsorption and diffusion

    J. Membr. Sci.

    (2017)
  • P. Van Hoogevest et al.

    Effect of amphotericin B on cholesterol-containing liposomes of egg phosphatidylcholine and didocosenoyl phosphatidylcholine. A refinement of the model for the formation of pores by amphotericin B in membranes

    Biochim. Biophys. Acta (BBA)-Biomembr.

    (1978)
  • V. Khutorsky

    Ion coordination in the amphotericin B channel

    Biophys. J.

    (1996)
  • H. Sun et al.

    The COMPASS force field: parameterization and validation for phosphazenes

    Comput. Theor. Polym. Sci.

    (1998)
  • J. Czub et al.

    Influence of a lipid bilayer on the conformational behavior of amphotericin B derivatives—a molecular dynamics study

    Biophys. Chem.

    (2009)
  • M. Baginski et al.

    Comparative molecular dynamics simulations of amphotericin B–cholesterol/ergosterol membrane channels

    Biochim. Biophys. Acta (BBA)-Biomembr.

    (2002)
  • J. Wijmans et al.

    The solution-diffusion model: a review

    J. Membr. Sci.

    (1995)
  • R.W. Baker

    Membrane Technology and Applications

    (2004)
  • A.P. Rao et al.

    Interfacially synthesized thin film composite RO membranes for seawater desalination

    J. Membr. Sci.

    (1997)
  • Y. Kaufman et al.

    Supported lipid bilayer membranes for water purification by reverse osmosis

    Langmuir

    (2010)
  • T.D. Lazzara et al.

    Separating attoliter-sized compartments using fluid pore-spanning lipid bilayers

    ACS Nano

    (2011)
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