Hydrophobic Association Research Articles

The driving force for co-translational protein folding is weaker in the ribosome vestibule due to greater water ordering.

Interactions between the ribosome and nascent chain can destabilize folded domains in the ribosome exit tunnel's vestibule, the last 3 nm of the exit tunnel where tertiary folding can occur. Here, we test if a contribution to this destabilization is a weakening of hydrophobic association, the driving force for protein folding. Using all-atom molecular dynamics simulations, we calculate the potential-of-mean force between two methane molecules along the center line of the ribosome exit tunnel and in bulk solution. Associated methanes, we find, are half as stable in the ribosome's vestibule as compared to bulk solution, demonstrating that the hydrophobic effect is weakened by the presence of the ribosome. This decreased stability arises from a decrease in the amount of water entropy gained upon the association of the methanes. And this decreased entropy gain originates from water molecules being more ordered in the vestibule as compared to bulk solution. Therefore, the hydrophobic effect is weaker in the vestibule because waters released from the first solvation shell of methanes upon association do not gain as much entropy in the vestibule as they do upon release in bulk solution. These findings mean that nascent proteins pass through a ribosome vestibule environment that can destabilize folded structures, which has the potential to influence co-translational protein folding pathways, energetics, and kinetics.

Inhibitory effects of functionalized polycarboxylate retarder on aberrant thickening phenomena of oil well cement at high temperature

Aberrant thickening of cement slurry caused by polycarboxylate retarders mainly refers to abnormal gelation and thickening time reversal (TTR) when temperature reaches above 120 °C. These phenomena would directly jeopardize cementing operation and hinder the application of polycarboxylate retarders in oil and gas exploitation. Herein, two functionalized polycarboxylate retarders were synthesized to overcome the challenges in complex conditions. The incorporation of isoprenyl oxy poly(ethyleneglycol) ether (TPEG) and [3-(methacryloylamino) propyl] trimethyl ammonium chloride (MAPTAC) was capable of preventing unfavorable “crosslinking and chelation” reaction between cement grains and polymer, thereby avoiding abnormal gelation. It was also found that the hydrophobic association behavior of long side chain in TPEG could cause the gradual release of carboxyl groups at elevated temperature, which was unfavorable for TTR inhibition. When the TPEG was replaced by N-Vinyl-2-Pyrrolidinone (NVP), its retarding effect gradually weakened when temperature rose from 130 °C to 150 °C, and excellent inhibition of TTR was achieved.

Hydrophobic and Hydrophilic Effects in a Mussel-Inspired Citrate-Based Adhesive.

The citrate-based tissue adhesive, synthesized by citric acid, diol, and dopamine, is a kind of mussel-inspired adhesive. The adhesion of mussel-inspired adhesive is not completely dependent on 3, 4-dihydroxyphenylalanine (Dopa) groups. The backbone structure of the adhesive also greatly affects the adhesion. In this study, to explore the effects of hydrophobicity and hydrophilicity of the backbone structure on adhesion, we prepared a series of citrate-based tissue adhesives (POEC-d) by changing the molar ratio of two diols, 1, 8-octanediol (O) and poly(ethylene oxide) (E), which formed hydrophobic segment units and hydrophilic segment units, respectively, in the molecule structure. The properties of cured adhesives showed that the adhesive with high E units had high swelling, rapid degradation, and low cohesion. In the adhesion strength measurement on the porcine skin, the adhesive with higher hydrophobicity was more likely to perform better. For the interfacial adhesion, hydrophilicity was conducive to the diffusion and penetration on the skin surface, but hydrophobic interaction showed a stronger effect to adhere with skin and hydrophobic association increased the adhesive concentration on the interface; for the bulk cohesion, hydrophobicity led to coacervation, promoting the Dopa-quinone coupling for cross-linking. In this amphipathic, citrate-based, soft-tissue adhesive system, when the feed ratio of hydrophilic segment was lower than 0.7, the coacervation could be formed through hydrophobic interaction, forming an efficient underwater adhesion system similar to that of mussels.

Associative structures formed from cellulose nanofibrils and nanochitins are pH-responsive and exhibit tunable rheology

HypothesisNanocellulose and nanochitin are both biobased materials with complementary structures and properties. Both exhibit pH-dependent surface charges which are opposite in sign. Hence, it should be possible to manipulate them to form complexed structures via ionic bond formation at prescribed pH conditions. ExperimentNanocellulose and nanochitin were mixed after exposure to acidic or neutral conditions to influence their ionization state. The heat of interaction during the introduction of nanochitin to nanocellulose was monitored via isothermal titration calorimetry. The strength and gel properties of the resulting structures were characterized via rheological measurement. FindingsThe resultant gel properties in the designed hybrid systems were found to depend directly on the charge state of the starting materials, which was dictated by pH adjustment. Different interparticle interactions including ionic attraction, hydrophobic associations, and physical entanglement were identified in the systems and the influence of each was elucidated for different conditions of pH, concentration, and ratio of nanochitin to nanocellulose. Hydrophobic associations between neutralized nanochitin particles were found to contribute strongly to increased elastic modulus values. Ionic complex formation was found to provide enhanced stability under broader pH conditions, while physical entanglement of cellulose nanofibers was a substantial thickening mechanism in all systems.

Molecular docking analysis of C-phycocyanin with VEGFR2.

C-phycocyanin (C-PC) produced from cyanobacterial species finds application in drug development. Therefore, it is of interest to document the molecular binding features of C-PC with the vascular endothelial growth factor receptor 2 (VEGFR2). C-PC showed H-bond interactions with residues on both sides of the Deusche Forschugsgemein-Schalt (DFG) loop (Asp1046-Phe1047-Gly1048). A hydrophobic association between the activation loop and the DFG residue (Gly1048) helps to inhibit the activity of VEGFR2 kinases. Thus, C-PC is reported as a potential angiogenesis inhibitor for VEGFR2 in combating cancer.

Dual‐responsive shape memory hydrogels with self‐healing and dual‐responsive swelling behaviors

AbstractShape memory hydrogels (SMHs) can fix the hydrogels in a provisional shape and restore the initial shape under external stimulation. Herein, a dual‐responsive shape memory hydrogel with dual‐responsive swelling and self‐healing properties is presented in this work. The SMHs were fabricated by one‐step emulsion copolymerization of acrylic acid (AAc), acrylamide (AAm) and stearyl methacrylate (SMA). Sodium alginate (SA) was introduced as an interpenetrating polymer in the network. With ionic cross‐linking between ‐COO− and Fe3+ or saline‐reinforced hydrophobic association, the hydrogels can be fixed in a provisional shape, which can be restored by immersing the hydrogels in vitamin C solution or pure water, respectively. When the as‐prepared hydrogels were immersed in FeCl3 solutions, additional ionic cross‐linking between Fe3+ and ‐COO− could be formed, thus constructing the dual physically cross‐linked (DPC) network, which endows the hydrogels with excellent fracture stress (2.6 MPa) and toughness (5.47 MJ/m3). Besides, the reversible physical cross‐linkings endowed the hydrogel with outstanding self‐healing capability. Furthermore, the pH and saline responsive swelling properties of the SMHs are additional fantastic properties. Therefore, we believe that this simple strategy provides a great opportunity for the preparation of SMHs with multiple intellectual performances.

Ultrahigh-water-content biocompatible gelatin-based hydrogels: Toughened through micro-sized dissipative morphology as an effective strategy

Fabrication of simultaneously robust and superabsorbent gelatin-based hydrogels for biomedical applications still remains a challenge due to lack of locally dissipative points in the presence of large water content. Here, we apply a synthesis strategy through which water absorbency and energy dissipative points are separated, and toughening mechanism is active closely at the crack tip. For this, gelatin-based microgels (GeMs) were synthesized in a way that concentrated supramolecular interactions were present to increase the energy necessary to propagate a macroscopic crack. The microgels were interlocked to each other via both temporary hydrophobic associations and permanent covalent crosslinks, in which the sacrificial binds sustained the toughness due to the mobility of the junction zones and particles sliding. However, chemical crosslinking points preserved the integrity and fast recoverability of the hydrogel. Hysteresis increased strongly with increasing supramolecular interactions within the network. The prepared hydrogels showed energy loss and swelling ratio up to 3440 J. m−3 and 830%, respectively, which was not achievable with conventional network fabrication methods. The microgels were also assessed for their in vivo biocompatibility in a rat subcutaneous pocket assay. Results of hematoxylin and eosin (H&E) staining demonstrated regeneration of the tissue around the scaffolds without incorporation of growth factors. Also, vascularization within the scaffolds was observed after 4 weeks implantation. These results indicate that our strategy is a promising method to manipulate those valuable polymers, which lose their toughness and applicability with increasing their water content.

Changes in aggregation properties of TPGS micelles in the presence of sodium cholate

D-alpha-tocopheryl polyethylene glycol 1000 succinate (TPGS), a nonionic surfactant, has been tested clinically for treating cholestatic liver disease. This research was aimed at investigating the effect of sodium cholate (NaC, a bile salt) on aggregation properties of TPGS. Changes in TPGS aggregates during NaC incorporation were investigated by UV–vis spectroscopy, electron microscopy, dynamic light scattering (DLS) and small angle neutron scattering (SANS). In pre-micelle concentration regime (≤10 mM), NaC molecules steadily migrated to the micelle core and no interfacial events were recorded in terms of changes in the cloud point and conductivity of dispersion. As a result of hydrophobic association between NaC and TPGS tail, micelles exhibited 20–30 % contraction. However, at higher concentration (≥20 mM), micelle core became crowded. Subsequently, NaC molecules were driven away from the core to shell region and swollen aggregates (200−300 nm) were formed. Movement of NaC to the shell region was confirmed from the bathochromic shift of methyl orange, encapsulated in the micelles. We reveal that hydrophobic interactions remarkably dominated under dehydrating effect of electrolytes, particularly under acidic conditions wherein NaC remains unionized. At intestinal pH, hydrophobic attraction appeared to be compensated by the electrostatic repulsion among ionized molecules; micelle dissociation occurred with 10 mM NaC. Our findings on TPGS-NaC interactions can be utilized to achieve successful bile salt sequestration.

High-strength and amphiphilic epoxidized soybean oil-modified poly(vinyl alcohol) hydrogels

Poly(vinyl alcohol) (PVA) hydrogels are widely used as biomimetic cartilage materials for its good biocompatibility and shock absorbing ability. However, the application of pure PVA hydrogel prepared through freezing–thawing method is limited by its disadvantages such as high flexibility and low mechanical strength. To solve these barriers, a biobased monomer, i.e., epoxidized soybean oil (ESO), was used to modify PVA to formulate a series of ESO cross-linked PVA (PVA-ESO) hydrogels. Infrared spectroscopy (FT-IR), X-ray diffraction and thermogravimetric analyses were used to confirm the formation of PVA-ESO copolymer. Scanning electron microscope revealed that the formed PVA-ESO hydrogels presented a distinct porous structure, while no obvious pores were observed on pure PVA hydrogel. The tensile strength of PVA-ESO hydrogels increased up to 2.4 times when compared to that of pure PVA hydrogel. Dynamic mechanical analysis indicated that the elastic properties of PVA-ESO hydrogels are better than that of pure PVA hydrogel, which are similar to that of natural cartilage. In summary, the modification of PVA with ESO can improve the thermal stability and mechanical properties of the hydrogels due to the improved cross-linking degree and the formed hydrophobic association.

Effect of micro‐aggregation behavior on the salt tolerance of polymer solutions

AbstractPolymer solution for oil displacement is mostly used in the middle and late stage of water flooding reservoir development, and reservoir groundwater conditions are often one of the main conditions restricting polymer application. Therefore, it is necessary to develop salt tolerance of polymer solutions with different aggregation behaviors, so as to facilitate the synthesis and optimization of suitable polymer systems. The differences in the micro‐aggregation behavior of three polymers with different molecular structures were explored. On this basis, the effects of divalent metal cations on the properties of the polymer solutions were analyzed by assessing the micro‐aggregation behavior, apparent viscosity, hydrodynamic size, and shear rheological characteristics. The results showed that the linear partially hydrolyzed polyacrylamide (HPAM) was seriously affected by divalent cations, and the viscosity decreased obviously. The aggregation behavior of the polymer changed by hydrophobic association can enhance the salt tolerance of the solution. The hydrophobically modified partially hydrolyzed polyacrylamide (HMPAM) with “chain beam” aggregation behavior has strong intermolecular connection, which enables it to withstand the content of calcium and magnesium ions of 1100 mg l−1. When the content of calcium and magnesium ions exceeds 600 mg l−1, dendritic hydrophobically associating polymer (DHAP) will destroy the interaction between molecular chains, resulting in the decrease of apparent viscosity and hydrodynamic size. For polymer flooding in high‐salinity reservoir, salt tolerant polymer system can be constructed by optimizing molecular weight and hydrophobic group content.

A graft-modification of chitosan with twin-tail hydrophobic association polymer for enhance oil recovery

With the development of oil and gas production technologies, some commonly used oilfield chemicals can no longer meet the requirements of production. A modified chitosan functional hydrophobic associative polymer CS-g-DLMB/AM/AA is synthesized by using a twin-tail monomer (DLMB), AM, and AA to graft-modify maleated chitosan in this study. The polymer was proved successful synthesis of the polymer. Through the study of rheological properties of polymers, CS-g-DLMB/AM/AA aqueous solution has excellent properties. The structure of chitosan enhances greatly the interaction force between the polymer molecular chains. The introduction of twin-tail improved the associative ability of the polymer molecular chain in water.

The flexible segment adjusted gelation of the aliphatic polycarbonates: Preparation, mechanical properties, and self-healing behavior

Many methods are used to improve the mechanical properties of hydrogels, but it is still challenging to generate comparable to natural hydrogels, let alone synchronously give it excellent self-healing properties. Herein, we synthesize a novel type of the aliphatic polycarbonate hydrogel with the above advantages. In this work, the ring-opening polymerization of 2-methyl-2-benzyloxy carbonyl propylene carbonate (MBC) and 1, 3-trimethylene carbonate (TMC) are initiated by the hydroxyl group of methoxy poly(ethylene glycol) (mPEG113, Mn = 5000). The effect of the TMC as flexible segments on the structure, mechanical properties, and self-healing behavior of the obtained materials is systematically studied. The swelling ratios of the obtained gels in water are enhanced as the content of the monomer TMC increases. The self-healing ability of the materials is drove by the hydrogen bonds and the hydrophobic associations to heal the fracture interfaces. The obtained gels exhibit outstanding mechanical properties and excellent ability of self-healing at room temperature. Both of these abilities can be adjusted by the variation of the TMC flexible segment. Thus, we provide a novel strategy for the fabrication of modified tough hydrogel, which will expand the modification field of hydrogels.

Highly Sensitive Pressure and Strain Sensors Based on Stretchable and Recoverable Ion-Conductive Physically Cross-Linked Double-Network Hydrogels.

Ion-conductive hydrogel sensors have attracted great research interests for applications in wearable devices, electronic skins, and implantable sensors, but most such sensors are fragile, with low conductivity and sensitivity. This study reports on novel ion-conductive double network hydrogels with a cross-linked helical structure, hydrophobic association, and metal-ion coordination. The helical κ-carrageenan first network and the second network cross-linked by Pluronic F127 diacrylate micelles and tridentate Fe3+-COO- coordination work synergistically to show the tensile strength of 2.7 MPa, fracture strain of 1400%, and tensile toughness of 9.82 MJ m-3 and fatigue resistance against cyclic loadings with high strains. The hydrogels show an ion conductivity of 1.15 S m-1, a strain sensitivity of up to 2.8, and a pressure sensitivity of 0.33 kPa-1. Sensor arrays fabricated from the conductive hydrogels provide an in-plane detection of pressures less than 200 Pa. Such hydrogel sensors have potential applications to electron skins and implantable sensors.

Synthesis of Amphiphilic Copolymers of Acrylic Acid and Styrene with the Desired Microstructure and Their Properties

The regularities of the controlled synthesis of amphiphilic copolymers of styrene and acrylic acid mediated by dithiobenzoate and trithiocarbonates as reversible addition fragmentation chain transfer agents in a 1,4-dioxane solution are considered. The influence of the general composition and chain microstructure on the dispersion stability and hydrodynamic sizes of polymer particles of copolymers containing from 40 to 90 mol % of acrylic acid units is studied. It is shown that in dilute aqueous media random copolymers are dispersed to individual compacted coils owing to the intrachain hydrophobic association of styrene units. The addition of two poly(acrylic acid) blocks to such a copolymer improves its dispersibility in water, and the attachment of two polystyrene blocks makes it insoluble in water because of the interchain association of polystyrene units. The synthesized copolymers possess surface activity, and when applied to a hydrophilic glass surface, they moderately hydrophobize it. In general, this synthetic approach opens up broad prospects for obtaining a wide range of new polymer macromolecules with different properties from one pair of traditional monomers.

A Thermal Thickening System Based on the Self-Assembly of a Zwitterionic Hydrophobic Association Polymer and Surfactant

The zwitterionic monomer, 1-(2-hydroxypropyl-sulfo)-acrylamide ethyl-N,N-dimethyl ammonium chloride (MeSA) was copolymerised with acrylamide (AM), acrylic acid (AA), and a hydrophobic monomer N,N-diallyl oleamide (DNDA) to obtain the zwitterionic hydrophobic association polymer AM/AA/DNDA/MeSA. The structure of the hydrophobic association polymer was characterised by 1H NMR, FT-IR, and intrinsic viscosity studies. The self-assembly system of the polymer and the surfactant Tween-40 was then formed, and the rheological properties and adsorptive performance of the self-assembly system were investigated. The result showed that the polymer–surfactant self-assembly system had good properties such as thickening, temperature resistance, salt resistance, and shear resistance. It is shown that the thermal thickening phenomenon, which allows the system to be used as a good petrochemical product in a high-temperature environment, provides a vital research foundation for the future application of this kind of self-assembly system.

Micelle Crosslinked Polyacrylic Acid Hydrogels with Resilience and Self‐Recovery Properties

AbstractMicelle crosslinking method is one of the several techniques to fabricate hydrogels with good mechanical performance. Micelle crosslinked hydrogels reported so far are fabricated using a multistep preparation process due to the functionalization of block copolymers or surfactants with acrylate, aldehyde, azo, or reversible addition‐fragmentation chain transfer groups to create a polymer network. Herein, a simple one‐step approach is introduced to produce resilient hydrogels prepared by bulk polymerization of acrylic acid and esterification with Triton X‐100 (TX‐100) in the presence of catalyst sulfuric acid (H2SO4). The advantage of this study is that TX‐100 surfactants self‐assembling into micelles are directly bonded onto polymer chains through an ester bond without any further modification. The obtained hydrogels exhibit tensile strengths up to 135 ± 8 kPa and compressive strengths up to 16 ± 1 MPa over 94% strains as well as complete self‐recovery and high resilience abilities (≈86% at strains up to 400%) originating from hydrophobic associations in the core of micelles acting as dynamic cross‐linkers along with hydrogen bonds and entanglements between polymer chains acting as additional crosslink points. The overall results show that the hydrogels can be good candidate as elastic materials in many fields.

Linking polymer hydrophobicity and molecular interactions to rheology and tribology in phospholipid-containing complex gels

HypothesisThe rheological behavior and frictional properties (macroscopic level) of systems containing a hydrophobically modified polymer and phospholipids depend on the hydrophobic association that occur between the hydrophobic moiety of the polymer and the phospholipid tails (molecular level). The hydrophobicity of the polymer can thus be used to control its interactions with phospholipids, and manipulate complex gel macroscopic behavior. ExperimentsBy using systems composed of a crosslinked hydrophobically modified polyacrylic acid (HMPAA) or a crosslinked polyacrylic acid polymer (PAA) and phospholipids, we examine the underlying mechanisms through which the components interact using isothermal titration calorimetry (ITC) and their effect on rheological and tribological characteristics of complex gels. FindingsWe find the systems containing HMPAA and phospholipid exhibit gel-like behavior with the elastic modulus increasing substantially upon phospholipid addition due to hydrophobic interactions that result in a more interconnected network formation, as evidenced by ITC measurements. Similar experiments with a crosslinked polyacrylic acid polymer (PAA) show no interactions, lending credence to our hypothesis. In addition, soft tribological behavior shows lower friction coefficients at low entrainment speeds with HMPAA concentration and the addition of phospholipid, while no change in friction coefficient was observed in the case of increasing PAA concentration, indicating HMPAA and phospholipids to be interacting with the soft PDMS contacts.

High‐viscoelastic graft modified chitosan hydrophobic association polymer for enhanced oil recovery

AbstractThe conventional partially hydrolyzed polyacrylamide (HPAM) is greatly restricted by its single linear molecular structure in oil reservoirs with severe reservoir conditions such as high temperature and high salt. In this article, the chitosan (CS) grafted imidazoline monomer copolymer (CS‐g‐AM/AA/NIDA) was prepared from N‐maleyl CS (N‐MCS), acrylamide (AM), acrylic acid (AA), 1‐(2‐N‐acryloylaminoethyl)‐2‐oleoyl imidazoline (NIDA) by free radical copolymerization. The structure was determined by means of Fourier transform infrared spectroscopy, 1H nuclear magnetic resonance spectroscopy, scanning electron microscope, thermal gravimetric analysis, and so forth, which confirmed the successful preparation of the copolymer with good thermal stability. Under the same conditions, compared with HPAM and copolymer CS‐g‐AM/AA, CS‐g‐AM/AA/NIDA greatly increased the viscosity of the aqueous solution and exhibited excellent shear stability (viscosity retention rate 15.62, 4.91, and 11.54% at 510 s−1), temperature resistance (the viscosity retention rate reached 50.89, 24.50, and 36.59% at 120°C) and salt resistance (14,000 mg/L NaCl: viscosity retention rate up to 17.27, 8.26, and 14.60%). In addition, core flooding experiments showed that oil recovery could be enhanced by up to 8.08% by CS‐g‐AM/AA/NIDA. As a natural polymer material, CS has hardly been reported for polymer flooding, and it is expected to replace general polymers in tertiary oil recovery.

Thermo-associating polymers based on cross-linked 2-acrylamido-methylpropane sulfonic acid, part B: Effect of co-solutes on solution behavior

Thermo-thickening copolymers have gained prominence in technological advancements due to its attractive properties and great potential to overcome the deficiency of viscosity of conventional copolymer upon increasing temperature and salinity. The work in this paper was devoted to examine the aqueous solution viscosity behavior of a new class thermo-thickening copolymer, poly(sodium 2-acrylamido-2-methylpropanesulfonic acid-co-N,N’-methylenebisacrylamide)-g-poly(acrylamide-co-N, N’-diethylacrylamide) denoted as CGBA in the presence of co-solutes. CGBA, which were reported in our previous work manifested notable viscosity enhancement macroscopically above the threshold temperature. However, the effect of small molecules on thermo-associative behavior was still unsettled. Based on structure/properties dependence of CGBA, this work aimed to explore the effect of small molecules and the role of molecular structure on aqueous solution viscosity behavior. The contributions of various added co-solutes such as anionic surfactant, acidic specie, monovalent and divalent salts were considered. For that purpose, three copolymers having distinctive composition of side-arms and length of side-arms were selected and their thermo-associating behaviors were followed by viscosity measurement. Results from rheological tests showed that these co-solutes induced notable modifications in the characteristic of thermo-thickening behavior. For all the co-solutes used, it was observed a strong dependence between the side-arms/water/co-solutes ternary system and the macroscopic property upon heating. Spectrofluorimetric and environmental scanning electron microscope (ESEM) tests were used to gain a deeper insight into the precise mechanism of phase transition process. Results from spectrofluorimetric experiment indicated that, only when the fraction of DEAm in CGBA was higher enough, it would appear strong abrupt macroscopic property above the threshold temperature, which could delay the offset of hydrophobic association phenomenon in the presence of anionic surfactant. Similar effect was also observed in the presence of added acidic specie. Conversely, the addition of monovalent and divalent salts showed dissimilar effects. ESEM revealed that, in comparison with monovalent salt, divalent salt favored the formation of larger and more condensed CGBA skeleton above the threshold temperature which led to an improved macroscopic response. This work demonstrates for the first time the micro-structure changes of copolymer, which was probably the main reason for the changes in magnitude of thermo-thickening effect in different divalent salt dosages.

Exploring the role of hydrophilic amino acids in unfolding of protein in aqueous ethanol solution.

Hydrophobic association is the key contributor behind the formation of well packed core of a protein which is often believed to be an important step for folding from an unfolded chain to its compact functional form. While most of the protein folding/unfolding studies have evaluated the changes in the hydrophobic interactions during chemical denaturation, the role of hydrophilic amino acids in such processes are not discussed in detail. Here we report the role of the hydrophilic amino acids behind ethanol induced unfolding of protein. Using free energy simulations, we show that chicken villin head piece (HP-36) protein unfolds gradually in presence of water-ethanol binary mixture with increasing composition of ethanol. However, upon mutation of hydrophilic amino acids by glycine while keeping the hydrophobic amino acids intact, the compact state of the protein is found to be stable at all compositions with gradual flattening of the free energy landscape upon increasing compositions. The local environment around the protein in terms of ethanol/water number significantly differs in wild type protein compared to the mutated protein. The calculated Wyman-Tanford preferential binding coefficient of ethanol for wild type protein reveals that a greater number of cosolutes (here ethanol) bind to the unfolded state compared to its folded state. However, no significant increase in binding coefficient of ethanol at the unfolded state is found for mutated protein. Local-bulk partition coefficient calculation also suggests similar scenarios. Our results reveal that the weakening of hydrophobic interactions in aqueous ethanol solution along with larger preferential binding of ethanol to the unfolded state mediated by hydrophilic amino acids combinedly helps unfolding of protein in aqueous ethanol solution.