Adsorption of the natural protein surfactant Rsn-2 onto liquid interfaces

The Journal of Chemical Physics

2017

Self Cite

As proteins contain both hydrophobic and hydrophilic amino acids, they will readily adsorb onto interfaces between water and hydrophobic fluids such as oil. This adsorption normally causes changes in the protein structure, which can result in loss of protein function and irreversible adsorption, leading to the formation of protein interfacial films. While this can be advantageous in some applications (e.g., food technology), in most cases it limits our ability to exploit protein functionality at interfaces. To understand and control protein interfacial adsorption and function, it is necessary to understand the microscopic conformation of proteins at liquid interfaces. In this paper, molecular dynamics simulations are used to investigate the adsorption and conformation of two similar proteins, lysozyme and α-lactalbumin, at a water-octane interface. While they both adsorb onto the interface, α-lactalbumin does so in a specific orientation, mediated by two amphipathic helices, while lysozyme adsorbs in a non-specific manner. Using replica exchange simulations, both proteins are found to possess a number of distinct interfacial conformations, with compact states similar to the solution conformation being most common for both proteins. Decomposing the different contributions to the protein energy at oil-water interfaces suggests that conformational change for α-lactalbumin, unlike lysozyme, is driven by favourable protein-oil interactions. Revealing these differences between the factors that govern the conformational change at interfaces in otherwise similar proteins can give insight into the control of protein interfacial adsorption, aggregation, and function.

Section: Discussionsupporting

confidence: 89%

Section: Lysozyme and α-Lactalbumin Adsorb To Water-octane Intermentioning

confidence: 91%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Adsorption and conformations of lysozyme and α-lactalbumin at a water-octane interface

The Journal of Chemical Physics

2017

Self Cite

“…The largely polar surface of Rsn-2 inhibits aggregation in solution but provides little driving force for interfacial adsorption. Atomistic molecular dynamics simulations [130] show that Rsn-2 adsorbs onto the air-water interface through its flexible N-terminus, which contains most of the solvent exposed hydrophobic residues. This is similar to the fly-casting mechanism often used in protein recognition [131].…”

Section: Ranaspuminmentioning

confidence: 99%

Molecular Dynamics Simulation of Protein Biosurfactants

Colloids and Interfaces

Samantray

2018

Surfaces and interfaces are ubiquitous in nature and are involved in many biological processes. Due to this, natural organisms have evolved a number of methods to control interfacial and surface properties. Many of these methods involve the use of specialised protein biosurfactants, which due to the competing demands of high surface activity, biocompatibility, and low solution aggregation may take structures that differ from the traditional head–tail structure of small molecule surfactants. As well as their biological functions, these proteins have also attracted interest for industrial applications, in areas including food technology, surface modification, and drug delivery. To understand the biological functions and technological applications of protein biosurfactants, it is necessary to have a molecular level description of their behaviour, in particular at surfaces and interfaces, for which molecular simulation is well suited to investigate. In this review, we will give an overview of simulation studies of a number of examples of protein biosurfactants (hydrophobins, surfactin, and ranaspumin). We will also outline some of the key challenges and future directions for molecular simulation in the investigation of protein biosurfactants and how this can help guide future developments.

“…Many of these have focused on the initial stages of interfacial adsorption, aiming to determine the factors that mediate protein adsorption [20][21][22] . Molecular dynamics simulations have also been used to investigate the interactions between proteins and inorganic ions at interfaces, giving insight into the process of biomineralization at interfaces 23,24 .…”

Section: Introductionmentioning

confidence: 99%

Adsorption and conformations of lysozyme andα-lactalbumin at a water-octane interface

2017

Preprint

Self Cite

As they contain both hydrophobic and hydrophilic amino acids proteins will readily adsorb onto interfaces between water and hydrophobic fluids such as oil. This adsorption normally causes changes in protein structure, which can result in a loss of protein function and irreversible adsorption, leading to the formation of protein interfacial films. While this can be advantageous in some applications (e.g. food technology) in most cases it limits our ability to exploit protein functionality at interfaces. To understand and control protein interfacial adsorption and function it is necessary to understand the microscopic conformation of proteins at liquid interfaces. In this paper molecular dynamics simulations are used to investigate the adsorption and conformation of two similar proteins, lysozyme and α-lactalbumin, at a water-octane interface. While they both adsorb onto the interface α-lactalbumin does so in a specific orientation, mediated by two amphipathic helices, while lysozyme adsorbs in a non-specific manner. Using replica exchange simulations both proteins are found to possess a number of distinct interfacial conformations, with compact states similar to the solution conformation being most common for both proteins. Decomposing the different contributions to the protein energy at oil-water interfaces, suggests that conformational change for α-lactalbumin, unlike lysozyme, is driven by favourable protein-oil interactions. Revealing these differences between the factors that govern conformational change at interfaces in otherwise similar proteins can give insight into the control of protein interfacial adsorption, aggregation, and function.