Interfacial layers from the protein HFBII hydrophobin: Dynamic surface tension, dilatational elasticity and relaxation times

Alexandrov, Nikola; Marinova, K. P.; Gurkov, Theodor D.; Danov, Krassimir D.; Kralchevsky, Peter A.; Stoyanov, Simeon D.; Blijdenstein, T.B.J.; Arnaudov, Luben N.; Pelan, Eddie G.; Lips, Alex

doi:10.1016/j.jcis.2012.03.031

Cited by 73 publications

(106 citation statements)

References 62 publications

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“…During regime II, the IFT decreases steeply until the interface is saturated with adsorbed protein, following which the IFT levels off (regime III), although a shallow gradient often indicates rearrangement of the protein layer. These characteristics can be seen in typical BslA dynamic interfacial tension response curves, however the fit error of the Young-Laplace equation to the droplet increased at some point during most experiments, indicating the formation of a viscoelastic layer (19).…”

Section: Resultsmentioning

confidence: 75%

“…5A shows the change in IFT of droplets of unfractionated WT-BslA suspended in air and in oil. The magnitude of the decrease in IFT caused by BslA was consistently smaller than the typical drop in IFT observed for the class II fungal hydrophobin HFBII at similar concentrations and timescales (19). This is perhaps not surprising as even a small energy barrier associated with a structural rearrangement has a significant impact on adsorption kinetics.…”

Section: The Crystal Structure Of Decameric Bsla Reveals Two Distinctmentioning

confidence: 78%

“…In this technique, the shape of a drop is fitted to the YoungLaplace equation to measure the interfacial tension (IFT) at the droplet surface (16,17), which decreases as the interface is populated by surface-active species (18). An increase in the error of the fit to the Young-Laplace equation indicates that a viscoelastic film has formed at the interface, and because a solid layer now separates the two liquid phases the concept of interfacial tension no longer applies (19). At low protein concentrations, the IFT initially remains unchanged for a lag time that is designated regime I (20,21).…”

Section: Resultsmentioning

confidence: 99%

“…; whereas, HFBII decreases the IFT to ∼56 mN·m −1 under the same conditions (19). However, despite this comparatively small decrease in IFT, an increase in the error of the Laplace fit (SI Appendix, Fig.…”

Section: The Crystal Structure Of Decameric Bsla Reveals Two Distinctmentioning

confidence: 87%

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Interfacial self-assembly of a bacterial hydrophobin

Bromley

Morris

Hobley

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

132

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The majority of bacteria in the natural environment live within the confines of a biofilm. The Gram-positive bacterium Bacillus subtilis forms biofilms that exhibit a characteristic wrinkled morphology and a highly hydrophobic surface. A critical component in generating these properties is the protein BslA, which forms a coat across the surface of the sessile community. We recently reported the structure of BslA, and noted the presence of a large surfaceexposed hydrophobic patch. Such surface patches are also observed in the class of surface-active proteins known as hydrophobins, and are thought to mediate their interfacial activity. However, although functionally related to the hydrophobins, BslA shares no sequence nor structural similarity, and here we show that the mechanism of action is also distinct. Specifically, our results suggest that the amino acids making up the large, surface-exposed hydrophobic cap in the crystal structure are shielded in aqueous solution by adopting a random coil conformation, enabling the protein to be soluble and monomeric. At an interface, these cap residues refold, inserting the hydrophobic side chains into the air or oil phase and forming a three-stranded β-sheet. This form then self-assembles into a wellordered 2D rectangular lattice that stabilizes the interface. By replacing a hydrophobic leucine in the center of the cap with a positively charged lysine, we changed the energetics of adsorption and disrupted the formation of the 2D lattice. This limited structural metamorphosis represents a previously unidentified environmentally responsive mechanism for interfacial stabilization by proteins.BslA | interfacial self-assembly | bacterial hydrophobin | Bacillus subtilis | biofilm

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Section: Resultsmentioning

confidence: 75%

Section: The Crystal Structure Of Decameric Bsla Reveals Two Distinctmentioning

confidence: 78%

Section: Resultsmentioning

confidence: 99%

Section: The Crystal Structure Of Decameric Bsla Reveals Two Distinctmentioning

confidence: 87%

See 2 more Smart Citations

Interfacial self-assembly of a bacterial hydrophobin

Bromley

Morris

Hobley

et al. 2015

Proc. Natl. Acad. Sci. U.S.A.

132

View full text Add to dashboard Cite

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“…Such portion covers about 12 % of HFBII total surface accessible area and is responsible of its amphiphilic behavior. HFBII has a molecular weight of about 7.2 kDa and an isoelectric point between 6 and 7 [28]. This relatively small protein (<3 nm diameter) can lower the air/water surface tension to 35 mN/m at a concentration of 30 μM [29].…”

Section: Introductionmentioning

confidence: 99%

Evaluating the potential of natural surfactants in the petroleum industry: the case of hydrophobins

Blešić

Dichiarante

Milani

et al. 2017

Pure and Applied Chemistry

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Enhancing oil recovery from currently available reservoirs is a major issue for petroleum companies. Among the possible strategies towards this, chemical flooding through injection of surfactants into the wells seems to be particularly promising, thanks to their ability to reduce oil/water interfacial tension that promotes oil mobilization. Environmental concerns about the use of synthetic surfactants led to a growing interest in their replacement with surfactants of biological origin, such as lipopeptides and glycolipids produced by several microorganisms. Hydrophobins are small amphiphilic proteins produced by filamentous fungi with high surface activity and good emulsification properties, and may represent a novel sustainable tool for this purpose. We report here a thorough study of their stability and emulsifying performance towards a model hydrocarbon mixture, in conditions that mimic those of real oil reservoirs (high salinity and high temperature). Due to the moderate interfacial tension reduction induced in such conditions, the application of hydrophobins in enhanced oil recovery techniques does not appear feasible at the moment, at least in absence of co-surfactants. On the other hand, the obtained results showed the potential of hydrophobins in promoting the formation of a gel-like emulsion 'barrier' at the oil/water interface.

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Building Reconfigurable Devices Using Complex Liquid–Fluid Interfaces

et al. 2019

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imparts novel mechanical and functional properties to the macroscopic interface itself. These properties include size-and charge-selective pathways for molecules and particulates, shear and compressive moduli, and selective binding and reaction sites. Complex interfaces can then be used to generate complex, macroscopic, all-liquid materials with very high surface areas that have unique properties, such as compartmentalization, communication between compartments, and the ability to move and reconfigure. With the rapid growth in the study of complex materials made from interfacially structured liquids, there is a need to review the field from the funda-Liquid-fluid interfaces provide a platform both for structuring liquids into complex shapes and assembling dimensionally confined, functional nanomaterials. Historically, attention in this area has focused on simple emulsions and foams, in which surface-active materials such as surfactants or colloids stabilize structures against coalescence and alter the mechanical properties of the interface. In recent decades, however, a growing body of work has begun to demonstrate the full potential of the assembly of nanomaterials at liquid-fluid interfaces to generate functionally advanced, biomimetic systems. Here, a broad overview is given, from fundamentals to applications, of the use of liquid-fluid interfaces to generate complex, all-liquid devices with a myriad of potential applications. Figure 2.Interactions between particles attached to liquid-fluid interfaces. a) Dipole-dipole interactions between adsorbed particles due to asymmetric charge distributions near the surface of particles at interfaces. Reproduced with permission. [34] Copyright 1980, American Physical Society. b) Dipole-dipole interactions give rise to 2D colloidal crystals with large lattice spacings. Scale bar, 50 µm. Reproduced with permission. [36]

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Interfacial layers from the protein HFBII hydrophobin: Dynamic surface tension, dilatational elasticity and relaxation times

Cited by 73 publications

References 62 publications

Interfacial self-assembly of a bacterial hydrophobin

Interfacial self-assembly of a bacterial hydrophobin

Evaluating the potential of natural surfactants in the petroleum industry: the case of hydrophobins

Building Reconfigurable Devices Using Complex Liquid–Fluid Interfaces

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