Academic literature on the topic 'Protein Conformation - Air/Water Interface'
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Journal articles on the topic "Protein Conformation - Air/Water Interface"
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Han, Fei, Qian Shen, Wei Zheng, Jingnan Zuo, Xinyu Zhu, Jingwen Li, Chao Peng, Bin Li, and Yijie Chen. "The Conformational Changes of Bovine Serum Albumin at the Air/Water Interface: HDX-MS and Interfacial Rheology Analysis." Foods 12, no. 8 (April 10, 2023): 1601. http://dx.doi.org/10.3390/foods12081601.
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The characterization and dynamics of protein structures upon adsorption at the air/water interface are important for understanding the mechanism of the foamability of proteins. Hydrogen–deuterium exchange, coupled with mass spectrometry (HDX-MS), is an advantageous technique for providing conformational information for proteins. In this work, an air/water interface, HDX-MS, for the adsorbed proteins at the interface was developed. The model protein bovine serum albumin (BSA) was deuterium-labeled at the air/water interface in situ for different predetermined times (10 min and 4 h), and then the resulting mass shifts were analyzed by MS. The results indicated that peptides 54–63, 227–236, and 355–366 of BSA might be involved in the adsorption to the air/water interface. Moreover, the residues L55, H63, R232, A233, L234, K235, A236, R359, and V366 of these peptides might interact with the air/water interface through hydrophobic and electrostatic interactions. Meanwhile, the results showed that conformational changes of peptides 54–63, 227–236, and 355–366 could lead to structural changes in their surrounding peptides, 204–208 and 349–354, which could cause the reduction of the content of helical structures in the rearrangement process of interfacial proteins. Therefore, our air/water interface HDX-MS method could provide new and meaningful insights into the spatial conformational changes of proteins at the air/water interface, which could help us to further understand the mechanism of protein foaming properties.
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Yano, Yohko F., Etsuo Arakawa, Wolfgang Voegeli, Chika Kamezawa, and Tadashi Matsushita. "Initial Conformation of Adsorbed Proteins at an Air–Water Interface." Journal of Physical Chemistry B 122, no. 17 (April 9, 2018): 4662–66. http://dx.doi.org/10.1021/acs.jpcb.8b01039.
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Lad, Mitaben D., Fabrice Birembaut, Joanna M. Matthew, Richard A. Frazier, and Rebecca J. Green. "The adsorbed conformation of globular proteins at the air/water interface." Physical Chemistry Chemical Physics 8, no. 18 (2006): 2179. http://dx.doi.org/10.1039/b515934b.
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Belem-Gonçalves, Silvia, Pascale Tsan, Jean-Marc Lancelin, Tito L. M. Alves, Vera M. Salim, and Françoise Besson. "Interfacial behaviour of bovine testis hyaluronidase." Biochemical Journal 398, no. 3 (August 29, 2006): 569–76. http://dx.doi.org/10.1042/bj20060485.
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The interfacial properties of bovine testicular hyaluronidase were investigated by demonstrating the association of hyaluronidase activity with membranes prepared from bovine testis. Protein adsorption to the air/water interface was investigated using surface pressure-area isotherms. In whichever way the interfacial films were obtained (protein injection or deposition), the hyaluronidase exhibited a significant affinity for the air/water interface. The isotherm obtained 180 min after protein injection into a pH 5.3 subphase was similar to the isotherm obtained after spreading the same amount of protein onto the same subphase, indicating that bovine testicular hyaluronidase molecules adopted a similar arrangement and/or conformation at the interface. Increasing the subphase pH from 5.3 to 8 resulted in changes of the protein isotherms. These modifications, which could correspond to the small pH-induced conformational changes observed by Fourier-transform IR spectroscopy, were discussed in relation to the pH influence on the hyaluronidase activity. Adding hyaluronic acid, the enzyme substrate, to the subphase tested the stability of the interfacial properties of hyaluronidase. The presence of hyaluronic acid in the subphase did not modify the protein adsorption and allowed substrate binding to a preformed film of hyaluronidase at pH 5.3, the optimal pH for the enzyme activity. Such effects of hyaluronic acid were not observed when the subphase was constituted of pure water, a medium where the enzyme activity was negligible. These influences of hyaluronic acid were discussed in relation to the modelled structure of bovine testis hyaluronidase where a hydrophobic region was proposed to be opposite of the catalytic site.
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Bhuvanesh, Thanga, Rainhard Machatschek, Yue Liu, Nan Ma, and Andreas Lendlein. "Self-stabilized fibronectin films at the air/water interface." MRS Advances 5, no. 12-13 (November 4, 2019): 609–20. http://dx.doi.org/10.1557/adv.2019.401.
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ABSTRACTFibronectin (FN) is a mediator molecule, which can connect cell receptors to the extracellular matrix (ECM) in tissues. This function is highly desirable for biomaterial surfaces in order to support cell adhesion. Controlling the fibronectin adsorption profile on substrates is challenging because of possible conformational changes after deposition, or due to displacement by secondary proteins from the culture medium. Here, we aim to develop a method to realize self-stabilized ECM glycoprotein layers with preserved native secondary structure on substrates. Our concept is the assembly of FN layers at the air-water (A-W) interface by spreading FN solution as droplets on the interface and transfer of the layer by the Langmuir-Schäfer (LS) method onto a substrate. It is hypothesized that 2D confinement and high local concentration at A-W interface supports FN self-interlinking to form cohesive films. Rising surface pressure with time, plateauing at 10.5 mN·m-1 (after 10 hrs), indicated that FN was self-assembling at the A-W interface. In situ polarization-modulation infrared reflection absorption spectroscopy of the layer revealed that FN maintained its native anti-parallel β-sheet structure after adsorption at the A-W interface. FN self-interlinking and elasticity was shown by the increase in elastic modulus and loss modulus with time using interfacial rheology. A network-like structure of FN films formed at the A-W interface was confirmed by atomic force microscopy after LS transfer onto Si-wafer. FN films consisted of native, globular FN molecules self-stabilized by intermolecular interactions at the A-W interface. Therefore, the facile FN self-stabilized network-like films with native anti-parallel β-sheet structure produced here, could serve as stable ECM protein coatings to enhance cell attachment on in vitro cell culture substrates and planar implant materials.
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Guo, Dashan, Yuwei Hou, Hongshan Liang, Lingyu Han, Bin Li, and Bin Zhou. "Mechanism of Reduced Glutathione Induced Lysozyme Defolding and Molecular Self-Assembly." Foods 12, no. 10 (May 9, 2023): 1931. http://dx.doi.org/10.3390/foods12101931.
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The distinctive assembly behaviors of lysozyme (Lys) feature prominently in food, materials, biomedicine, and other fields and have intrigued many scholars. Although our previous work suggested that reduced glutathione (GSH) could induce lysozyme to form interfacial films at the air/water interface, the underlying mechanism is still obscure. In the present study, the effects of GSH on the disulfide bond and protein conformation of lysozyme were investigated by fluorescence spectroscopy, circular dichroism spectroscopy, and infrared spectroscopy. The findings demonstrated that GSH was able to break the disulfide bond in lysozyme molecules through the sulfhydryl/disulfide bond exchange reaction, thereby unraveling the lysozyme. The β-sheet structure of lysozyme expanded significantly, while the contents of α-helix and β-turn decreased. Furthermore, the interfacial tension and morphology analysis supported that the unfolded lysozyme tended to arrange macroscopic interfacial films at the air/water interface. It was found that pH and GSH concentrations had an impact on the aforementioned processes, with higher pH or GSH levels having a positive effect. This paper on the exploration of the mechanism of GSH-induced lysozyme interface assembly and the development of lysozyme-based green coatings has better instructive significance.
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Renault, Anne, Jean-François Rioux-Dubé, Thierry Lefèvre, Stéphane Pezennec, Sylvie Beaufils, Véronique Vié, Mélanie Tremblay, and Michel Pézolet*. "Surface Properties and Conformation of Nephila clavipes Spider Recombinant Silk Proteins at the Air−Water Interface." Langmuir 25, no. 14 (July 21, 2009): 8170–80. http://dx.doi.org/10.1021/la900475q.
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Han, Meng-huai, and Chi-cheng Chiu. "Fast estimation of protein conformational preference at air/water interface via molecular dynamics simulations." Journal of the Taiwan Institute of Chemical Engineers 92 (November 2018): 42–49. http://dx.doi.org/10.1016/j.jtice.2018.02.026.
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Flach, Carol R., Joseph W. Brauner, and Richard Mendelsohn. "Coupled External Reflectance FT-IR/Miniaturized Surface Film Apparatus for Biophysical Studies." Applied Spectroscopy 47, no. 7 (July 1993): 982–85. http://dx.doi.org/10.1366/0003702934415147.
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An FT-IR spectrophotometer has been interfaced to a miniaturized surface film apparatus for external reflection studies of insoluble monolayers in situ at the air/water interface. Signal-to-noise ratios of 200:1 were routinely achieved for the CH2 stretching vibrations of phospholipids. We have monitored, using the acyl chain symmetric CH2 stretching frequency near 2850 cm−1 as a structural probe, lipid conformational order changes that occur during the surface pressure-induced two-dimensional phase transition in monolayers of 1,2-dipalmitoylphosphatidylserine. In addition, the small volume of the miniaturized film apparatus (30 mL) permitted replacement of H2O with D2O in the subphase. This capability, in turn, permits the acquisition of spectral data in the amide I region of proteins. We report the first external reflection FT-IR spectrum of an insoluble protein monolayer. The protein studied is pulmonary surfactant SP-C.
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Tanaka, Takumi, Yuki Terauchi, Akira Yoshimi, and Keietsu Abe. "Aspergillus Hydrophobins: Physicochemical Properties, Biochemical Properties, and Functions in Solid Polymer Degradation." Microorganisms 10, no. 8 (July 25, 2022): 1498. http://dx.doi.org/10.3390/microorganisms10081498.
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Hydrophobins are small amphipathic proteins conserved in filamentous fungi. In this review, the properties and functions of Aspergillus hydrophobins are comprehensively discussed on the basis of recent findings. Multiple Aspergillus hydrophobins have been identified and categorized in conventional class I and two non-conventional classes. Some Aspergillus hydrophobins can be purified in a water phase without organic solvents. Class I hydrophobins of Aspergilli self-assemble to form amphipathic membranes. At the air–liquid interface, RolA of Aspergillus oryzae self-assembles via four stages, and its self-assembled films consist of two layers, a rodlet membrane facing air and rod-like structures facing liquid. The self-assembly depends mainly on hydrophobin conformation and solution pH. Cys4–Cys5 and Cys7–Cys8 loops, disulfide bonds, and conserved Cys residues of RodA-like hydrophobins are necessary for self-assembly at the interface and for adsorption to solid surfaces. AfRodA helps Aspergillus fumigatus to evade recognition by the host immune system. RodA-like hydrophobins recruit cutinases to promote the hydrolysis of aliphatic polyesters. This mechanism appears to be conserved in Aspergillus and other filamentous fungi, and may be beneficial for their growth. Aspergilli produce various small secreted proteins (SSPs) including hydrophobins, hydrophobic surface–binding proteins, and effector proteins. Aspergilli may use a wide variety of SSPs to decompose solid polymers.
Dissertations / Theses on the topic "Protein Conformation - Air/Water Interface"
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Kim, Chanjoong. "Molecular conformation and dynamics of amphiphiles monolayers at the air/water interface." 2003. http://www.library.wisc.edu/databases/connect/dissertations.html.
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Meng-HuaiHan and 韓孟淮. "Free Energy Analysis of Protein Folding and Adsorption at the Air/Water Interface." Thesis, 2017. http://ndltd.ncl.edu.tw/handle/689gn7.
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碩士國立成功大學
化學工程學系
105
Proteins are biological polymers that play many important roles in biological systems. The protein functions are highly correlated with the protein structures, which are affected by the solvent pH, temperature, and concentrations, etc. Protein have been applied in various fields, such as the substrate surface modifications, or the detecting molecules in the biosensors. In order to probe the effects of adsorbed interface on the protein structures, we investigate the protein conformational changes at the air/water interfaces for four different groups of proteins with different secondary structural characteristics, i.e. α-helix native, β-hairpin native, protein with equal α- and β-probability, and small amyloid peptide fibrils. We applied molecular dynamics combined with methadyanmics to calculate the protein conformational free energies in bulk water and at air/water interface. Furthermore, we developed a thermodynamics model for protein adsorption that focuses on two contributions, i.e. the desolvation of peptide residues and the reduction of air-water interfacial energy. Via the comparison between the peptide adsorption free energies at the air/water interface obtain by the theoretical prediction and simulation data, we found the proposed thermodynamic model accurately predicted the relative adsorption free energies of peptide in different conformations. Combining the protein adsorption free energies estimated from the thermodynamic model and the conformational free energy calculated from MD simulations, the complete thermodynamic cycle of protein adsorption and conformational change can be constructed. The results showed that the air/water interfacial energy changes, caused by the peptide allocation at the interface that inclines the air/water contact, are the main driving force of the protein adsorbing at the interface. Furthermore, the stability of protein secondary structure is also affected by the desolvation of the amino acid exposed to the air phase. Hence, the peptide sequence is important for the protein secondary structural preference at the interface. The model was further applied to investigate the adsorption free energy of small amyloid peptide fibrils. Our results showed that, owing to the arrangement of hydrophobic residues, the adsorbing fibril face play important roles for amyloid fibril adsorption at the air/water interface.
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Rajdev, Priya. "Orienting Macromolecule At The Air - Water Interface : DNA-Protein Interaction On Langmuir Films." Thesis, 2008. https://etd.iisc.ac.in/handle/2005/781.
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The Langmuir – Blodgett (LB) technique is about forming insoluble monolayer on the surface of aqueous solution and recently, it has emerged as one of the best method to study floating monolayer at the air – water interface. It has gained popularity after the use of monolayer with chemical complexes as well as biological species, and recently it has been used for the formation of biosensors. Langmuir monolayer arrays the amphiphilic molecules in a fashion where the hydrophobic part points towards the air and the hydrophilic group remains in contact with the aqueous subphase. Due to this property of Langmuir monolayer to orient the molecules at the air – water interface in a particular fashion, it can successfully serve as a template for two – dimensional reactions with restricted freedom. Hence, Langmuir monolayer has been extensively employed to study chemical and biological reactions at the air – water interface.
To understand the behavior of Langmuir monolayer, surface pressure – molecular area (P – A) isotherms are studied as these P – A isotherms illustrate general conditions regarding the phase behavior of the two-dimensional Langmuir monolayer. Any change occurring due to the alignment of aliphatic molecules forming the monolayer is reflected by the change in P – A isotherms, which is known as phase transition. The phase transition is the most important element of the P – A isotherms with a characteristic signature of a plateau region in the isotherms. This phase transition point changes with the change of certain external parameters such as temperature, pH, and ionic strength, and as a result gives general information regarding the phase transition behavior. Therefore, with the little change of external parameters, the arrangement of the molecules in the monolayer also changes, which is reflected in the change in the nature of the isotherms. Thus, the system can, in principle, be used to define several physical parameters associated with it.
On account of the property of Langmuir monolayer to orient the molecules at the air – water interface with restricted mobility and due to their condensed nature known as solid like phase, it closely mimics the situation inside a biological cell. Hence, we wanted to test whether an artificial nucleus can be generated at LB films. This can be achieved by immobilizing DNA or protein at the air – water interface and then by promoting their biological properties through macromolecular recognition. Here, immobilization of a macromolecule of biological relevance, its interaction with another component of a cell and extracting the thermodynamic parameters utilizing the LB technique will be of significance. This thesis embodies the immobilization of some biologically important proteins then follows their activity as well as DNA recognition properties at the air – water interface. A set of equations are derived here for the two dimensional Langmuir monolayer, which are used to calculate the thermodynamics of the system under study.
Chapter 1 outlines the information about Langmuir monolayer and LB films. It sketches the historical background of the Langmuir monolayer and also elucidates the theory behind the same. This chapter cites the technical details of formation of Langmuir monolayer and LB films viś – a – viś other methods available for the fabrication of monomolecular films. It adequately discusses the functional LB films and their utilization for various different purposes. Finally, the role of metal ions in the LB films and in immobilizing biological macromolecules is discussed.
Chapter 2 discusses the different techniques employed to perform the experiments described in this thesis. It includes the purification methods for the different proteins and DNA; the details of formation of Langmuir monolayer and fabrication of LB films. This chapter also describes the various techniques used for the characterization of the LB films, i.e Atomic Force Microscopy (AFM) and Fourier Transform Infrared (FTIR) spectroscopy.
In Chapter 3, immobilization and imaging of protein molecules and protein DNA complexes on a LB substrate have been explored. Firstly, we describe the preparation of a Ni (II) – arachidate (NiA) monolayer and its characterization through P – A isotherm on a LB trough. Then, recombinant RNA polymerase from Escherichia coli, where the largest subunit was replaced with the same gene having a series of histidine amino acids at the C-terminus end of the protein, was immobilized over the NiA monolayer through a Ni (II) – histidine interaction. A single molecule of RNA polymerase (RNAP) could be seen through intermittent-contact AFM. Under the condition of the formation of the LB monolayer, the enzyme molecules were arrayed and transcriptionally active. Interestingly, they could pick up sequence specific DNA molecules from the subphase in an oriented fashion.
In Chapter 4, the interaction between NiA and histidine tagged RNAP (HisRNAP), and RNAP and DNA were studied. LB films of Arachidic acid – NiA, NiA -HisRNAP and NiA – HisRNAP – DNA with different mole fractions were fabricated systematically. P -A isotherms were registered, and the excess Gibbs energy of mixing was calculated. The LB films were then deposited on solid supports for FTIR spectroscopic measurements. The FTIR spectra revealed the change in the amount of incorporated Ni (II) ions into the AA monolayer with the change in pH. The increase in mole fraction of RNAP and DNA in the NiA and NiA – RNAP monolayer, respectively, with their increasing concentration in the subphase are also noticed. The system developed here is robust and can be utilized to follow macromolecular interactions.
In chapter 5, the Langmuir monolayer has been utilized to array a protein, Dps, specific for Fe (II) and non-specific for DNA. Dps from Mycobacterium smegmatis is known to have a cage like structure, exists in two oligomeric states, trimer and dodecamer, and can accommodate Fe (II) ions in its internal cavity. In addition, it converts Fe (II) to Fe (III), both in trimeric and dodecameric form, whereas the latter species is specific for non-specific DNA binding. We demonstrate here that, histidine tagged Dps in both oligomeric states can be immobilized on NiA LB films, where both ferroxidation and DNA binding ability remained unaffected in the ordered protein assembly. Interestingly, when Fe (II) – arachidate was used to generate a LB layer instead of NiA, Dps protein not only recognizes Fe (II) ion in the monolayer, it also converts it to Fe (III) ion in a time dependent fashion. However, once Fe (III) – Dps complex is formed and arrayed on LB monolayers, it remains very stable.
4
Rajdev, Priya. "Orienting Macromolecule At The Air - Water Interface : DNA-Protein Interaction On Langmuir Films." Thesis, 2008. http://hdl.handle.net/2005/781.
Full textAbstract:
The Langmuir – Blodgett (LB) technique is about forming insoluble monolayer on the surface of aqueous solution and recently, it has emerged as one of the best method to study floating monolayer at the air – water interface. It has gained popularity after the use of monolayer with chemical complexes as well as biological species, and recently it has been used for the formation of biosensors. Langmuir monolayer arrays the amphiphilic molecules in a fashion where the hydrophobic part points towards the air and the hydrophilic group remains in contact with the aqueous subphase. Due to this property of Langmuir monolayer to orient the molecules at the air – water interface in a particular fashion, it can successfully serve as a template for two – dimensional reactions with restricted freedom. Hence, Langmuir monolayer has been extensively employed to study chemical and biological reactions at the air – water interface.
To understand the behavior of Langmuir monolayer, surface pressure – molecular area (P – A) isotherms are studied as these P – A isotherms illustrate general conditions regarding the phase behavior of the two-dimensional Langmuir monolayer. Any change occurring due to the alignment of aliphatic molecules forming the monolayer is reflected by the change in P – A isotherms, which is known as phase transition. The phase transition is the most important element of the P – A isotherms with a characteristic signature of a plateau region in the isotherms. This phase transition point changes with the change of certain external parameters such as temperature, pH, and ionic strength, and as a result gives general information regarding the phase transition behavior. Therefore, with the little change of external parameters, the arrangement of the molecules in the monolayer also changes, which is reflected in the change in the nature of the isotherms. Thus, the system can, in principle, be used to define several physical parameters associated with it.
On account of the property of Langmuir monolayer to orient the molecules at the air – water interface with restricted mobility and due to their condensed nature known as solid like phase, it closely mimics the situation inside a biological cell. Hence, we wanted to test whether an artificial nucleus can be generated at LB films. This can be achieved by immobilizing DNA or protein at the air – water interface and then by promoting their biological properties through macromolecular recognition. Here, immobilization of a macromolecule of biological relevance, its interaction with another component of a cell and extracting the thermodynamic parameters utilizing the LB technique will be of significance. This thesis embodies the immobilization of some biologically important proteins then follows their activity as well as DNA recognition properties at the air – water interface. A set of equations are derived here for the two dimensional Langmuir monolayer, which are used to calculate the thermodynamics of the system under study.
Chapter 1 outlines the information about Langmuir monolayer and LB films. It sketches the historical background of the Langmuir monolayer and also elucidates the theory behind the same. This chapter cites the technical details of formation of Langmuir monolayer and LB films viś – a – viś other methods available for the fabrication of monomolecular films. It adequately discusses the functional LB films and their utilization for various different purposes. Finally, the role of metal ions in the LB films and in immobilizing biological macromolecules is discussed.
Chapter 2 discusses the different techniques employed to perform the experiments described in this thesis. It includes the purification methods for the different proteins and DNA; the details of formation of Langmuir monolayer and fabrication of LB films. This chapter also describes the various techniques used for the characterization of the LB films, i.e Atomic Force Microscopy (AFM) and Fourier Transform Infrared (FTIR) spectroscopy.
In Chapter 3, immobilization and imaging of protein molecules and protein DNA complexes on a LB substrate have been explored. Firstly, we describe the preparation of a Ni (II) – arachidate (NiA) monolayer and its characterization through P – A isotherm on a LB trough. Then, recombinant RNA polymerase from Escherichia coli, where the largest subunit was replaced with the same gene having a series of histidine amino acids at the C-terminus end of the protein, was immobilized over the NiA monolayer through a Ni (II) – histidine interaction. A single molecule of RNA polymerase (RNAP) could be seen through intermittent-contact AFM. Under the condition of the formation of the LB monolayer, the enzyme molecules were arrayed and transcriptionally active. Interestingly, they could pick up sequence specific DNA molecules from the subphase in an oriented fashion.
In Chapter 4, the interaction between NiA and histidine tagged RNAP (HisRNAP), and RNAP and DNA were studied. LB films of Arachidic acid – NiA, NiA -HisRNAP and NiA – HisRNAP – DNA with different mole fractions were fabricated systematically. P -A isotherms were registered, and the excess Gibbs energy of mixing was calculated. The LB films were then deposited on solid supports for FTIR spectroscopic measurements. The FTIR spectra revealed the change in the amount of incorporated Ni (II) ions into the AA monolayer with the change in pH. The increase in mole fraction of RNAP and DNA in the NiA and NiA – RNAP monolayer, respectively, with their increasing concentration in the subphase are also noticed. The system developed here is robust and can be utilized to follow macromolecular interactions.
In chapter 5, the Langmuir monolayer has been utilized to array a protein, Dps, specific for Fe (II) and non-specific for DNA. Dps from Mycobacterium smegmatis is known to have a cage like structure, exists in two oligomeric states, trimer and dodecamer, and can accommodate Fe (II) ions in its internal cavity. In addition, it converts Fe (II) to Fe (III), both in trimeric and dodecameric form, whereas the latter species is specific for non-specific DNA binding. We demonstrate here that, histidine tagged Dps in both oligomeric states can be immobilized on NiA LB films, where both ferroxidation and DNA binding ability remained unaffected in the ordered protein assembly. Interestingly, when Fe (II) – arachidate was used to generate a LB layer instead of NiA, Dps protein not only recognizes Fe (II) ion in the monolayer, it also converts it to Fe (III) ion in a time dependent fashion. However, once Fe (III) – Dps complex is formed and arrayed on LB monolayers, it remains very stable.
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Perriman, Adam Willis. "The effect of the air-water interface on protein structure : a neutron and X-ray reflectometry study." Phd thesis, 2006. http://hdl.handle.net/1885/149756.
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Leapard, James Brian. "A custom fluorescence microscope for the observation of surface morphology at the air-water interface and an investigation of surface association and structure of deacylated surfactant protein C." 2002. http://purl.galileo.usg.edu/uga%5Fetd/leapard%5Fjames%5Fb%5F200212%5Fms.
Full textBook chapters on the topic "Protein Conformation - Air/Water Interface"
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Narváez, Alfredo R., and Shyam V. Vaidya. "Protein—Surfactant Interactions at the Air-Water Interface." In Excipient Applications in Formulation Design and Drug Delivery, 139–66. Cham: Springer International Publishing, 2015. http://dx.doi.org/10.1007/978-3-319-20206-8_6.
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Bussières, Sylvain, Julie Boucher, Philippe Desmeules, Michel Grandbois, Bernard Desbat, and Christian Salesse. "Monitoring of Membrane-Associated Protein Binding and of Enzyme Activity in Monolayers at the Air-Water Interface by Infrared Spectroscopy." In Structure and Dynamics of Membranous Interfaces, 165–89. Hoboken, NJ, USA: John Wiley & Sons, Inc., 2014. http://dx.doi.org/10.1002/9780470388495.ch7.
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"Protein Interactions with Monolayers at the Air-Water Interface." In Biopolymers at Interfaces, 432–51. CRC Press, 2003. http://dx.doi.org/10.1201/9780824747343-17.
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Jogikalmath, G., David Britt, and Vladimir Hlady. "Protein Interactions with Monolayers at the Air –Water Interface." In Surfactant Science. CRC Press, 2003. http://dx.doi.org/10.1201/9780824747343.ch16.
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Wasserman, L. A., and M. G. Semenova. "Effect of Lipophilic Molecules on Food Protein Surface Activity at the Air–Water Interface." In Food Colloids, 77–91. Elsevier, 2004. http://dx.doi.org/10.1533/9781845698263.2.77.
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"The Dynamics of Formation and Structure of the Air–Water Interface in the Presence of Protein – Polysaccharide Mixtures." In Water Properties of Food, Pharmaceutical, and Biological Materials, 461–70. CRC Press, 2006. http://dx.doi.org/10.1201/9781420001181-31.
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Brisson, A., and O. Lambert. "Two-Dimensional Crystallization of Soluble Proteins on Planar Lipid Films." In Crystallization of Nucleic Acids and Proteins. Oxford University Press, 1999. http://dx.doi.org/10.1093/oso/9780199636792.003.0016.
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Electron crystallography of protein two-dimensional (2D) crystals constitutes a fast-expanding method for determining the structure of macromolecules at near-atomic resolution (1, 2). The main limitation in the application and generalization of this approach remains in obtaining highly ordered 2D crystals, as is the case of 3D crystals in X-ray crystallography. Several methods of 2D crystallization are available which can be classified into two families, depending on the type of proteins under investigation, either membrane proteins (3, 4) or soluble proteins (5, 6). In both cases, 2D crystallization is a self-organization process which spontaneously occurs between macromolecules which are restricted to diffusing by translation and rotation in a 2D space, with a fixed orientation along the normal to this plane. The scope of this chapter is restricted to the 2D crystallization of soluble proteins on planar lipid films, by the so-called ‘lipid monlayer crystallization method’ (5). Our aim is to present a step-by-step description of the experimental procedures involved in the application of this method. The method of protein 2D crystallization on planar lipid films was introduced about 15 years ago (5) and has since been successfully applied to about 30 proteins. Its principle is based on the specific interaction between soluble proteins and lipid ligands inserted in a lipid monolayer, at an air-water interface. In practice, a lipid monolayer is formed by spreading lipids dissolved in an organic solvent on a water surface. Proteins present in the aqueous subphase bind to their ligand of lipidic nature and spontaneously form 2D domains and, in favourable cases, 2D crystals. The process of 2D crystal formation relies on three successive steps: (a) Molecular recognition between a protein and its ligand. (b) Diffusion and concentration of the protein-lipid complexes in the plane of the lipid film. (c) Self-organization of the proteins into 2D crystals. As indicated in Table 1, three different types of systems can be distinguished, depending on the nature of the lipid ligand: • natural lipids • synthetic lipids made of a protein ligand coupled to a lipid molecule • charged lipids.
Conference papers on the topic "Protein Conformation - Air/Water Interface"
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Chang, Liuyi, and Jiajia Rao. "The role of conformational state of pea protein fractions on the oil/water dynamic adsorption, rheological interfacial properties and emulsifying properties." In 2022 AOCS Annual Meeting & Expo. American Oil Chemists' Society (AOCS), 2022. http://dx.doi.org/10.21748/zjao7478.
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Recently, the utilization of pea protein is on the rise because of its low price and nutritional benefits. However, the application of pea proteins is still limited by its functional properties as compared to other plant proteins due to insufficient research, especially in structure-functionality relationship among individual pea protein fractions. Regarding the functional properties, emulsifying properties is one of the important functional properties of protein. It is well established that the emulsifying properties of protein is affected by protein composition, structural properties and environmental factors. As such, the aim of this study was to investigate the impact of environmental pHs (3, 7, 9) and different salt concentrations (20 mM, 200 mM) on protein structure, kinetic adsorption and rheological interfacial properties of pea protein fractions (globulin, legumin, vicilin and albumin) at the oil/water interface, and then to research its relationship with emulsifying properties. The results showed that the addition of NaCl had a greater impact when compared to pH for all tested pea protein fractions in a number of direction. For instance, the secondary structure of the protein was changed, the ability of the protein to increase the interfacial pressure (π) was reduced. Consequently, the emulsifying capacity was also decreased. With regard to the fraction effect, legumin subunit had higher emulsifying stability when compared to vicilin. For example, the particle size of legumin stabilized emulsion increased slightly, but that of vicilin stabilized emulsion droplet increased dramatically (from 4.78 to 19.43 μm) after 24 h storage at pH 3. This phenomenon might be attributed to the higher macromolecular interactions of vicilin at oil/water interface (e.g., the slopes of E- π plots were 2.18 legumin vs 3.19 vicilin). The research results could provide valuable information on molecular mechanism of emulsifying properties of pea protein fractions.
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Smiley, Beth L., and Viola Vogel. "Nonlinear optical characterization of aromatic amino acids at the air/water interface: intrinsic probes of protein ordering on surfaces." In OE/LASE '94, edited by Hai-Lung Dai and Steven J. Sibener. SPIE, 1994. http://dx.doi.org/10.1117/12.180869.
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Chen, Kok Hao, and Jong Hyun Choi. "DNA Oligonucleotide-Templated Nanocrystals: Synthesis and Novel Label-Free Protein Detection." In ASME 2009 International Mechanical Engineering Congress and Exposition. ASMEDC, 2009. http://dx.doi.org/10.1115/imece2009-11958.
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Semiconductor and magnetic nanoparticles hold unique optical and magnetic properties, and great promise for bio-imaging and therapeutic applications. As part of their stable synthesis, the nanocrystal surfaces are usually capped by long chain organic moieties such as trioctylphosphine oxide. This capping serves two purposes: it saturates dangling bonds at the exposed crystalline lattice, and it prevents irreversible aggregation by stabilizing the colloid through entropic repulsion. These nanocrystals can be rendered water-soluble by either ligand exchange or overcoating, which hampers their widespread use in biological imaging and biomedical therapeutics. Here, we report a novel scheme of synthesizing fluorescent PbS and magnetic Fe3O4 nanoparticles using DNA oligonucleotides. Our method of PbS synthesis includes addition of Na2S to the mixture solution of DNA sequence and Pb acetate (at a fixed molar ratio of DNA/S2−/Pb2+ of 1:2:4) in a standard TAE buffer at room temperature in the open air. In the case of Fe3O4 particle synthesis, ferric and ferrous chloride were mixed with DNA in DI water at a molar ratio of DNA/Fe2+/Fe3+ = 1:4:8 and the particles were formed via reductive precipitation, induced by increasing pH to ∼11 with addition of ammonium hydroxide. These nanocrystals are highly stable and water-soluble immediately after the synthesis, due to DNA termination. We examined the surface chemistry between oligonucleotides and nanocrystals using FTIR spectroscopy, and found that the different chemical moieties of nucleobases passivate the particle surface. Strong coordination of primary amine and carbonyl groups provides the chemical and colloidal stabilities, leading to high particle yields (Figure 1). The resulting PbS nanocrystals have a distribution of 3–6 nm in diameter, while a broader size distribution is observed with Fe3O4 nanoparticles as shown in Figure 1b and c, respectively. A similar observation was reported with the pH change-induced Fe3O4 particles of a bimodal size distribution where superparamagnetic and ferrimagnetic magnetites co-exist. In spite of the differences, FTIR measurements suggest that the chemical nature of the oligonucleotide stabilization in this case is identical to the PbS system. As a particular application, we demonstrate that aptamer-capped PbS QD can detect a target protein based on selective charge transfer, since the oligonucleotide-templated synthesis can also serve the additional purpose of providing selective binding to a molecular target. Here, we use thrombin and a thrombin-binding aptamer as a model system. These QD have diameters of 3∼6 nm and fluoresce around 1050 nm. We find that a DNA aptamer can passivate near IR fluorescent PbS nanocrystals, rendering them water-soluble and stable against aggregation, and retain the secondary conformation needed to selectively bind to its target, thrombin, as shown in Figure 2. Importantly, we find that when the aptamer-functionalized nanoparticles binds to its target (only the target), there is a highly systematic and selective quenching of the PL, even in high concentrations of interfering proteins as shown in Figure 3a and b. Thrombin is detected within one minute with a detection limit of ∼1 nM. This PL quenching is attributed to charge transfer from functional groups on the protein to the nanocrystals. A charge transfer can suppress optical transition mechanisms as we observe a significant decrease in QD absorption with target addition (Figure 3c). Here, we rule out other possibilities including Forster resonance energy transfer (FRET) and particle aggregation, because thrombin absorb only in the UV, and we did not observe any significant change in the diffusion coefficient of the particles with the target analyte, respectively. The charge transfer-induced photobleaching of QD and carbon nanotubes was observed with amine groups, Ru-based complexes, and azobenzene compounds. This selective detection of an unlabeled protein is distinct from previously reported schemes utilizing electrochemistry, absorption, and FRET. In this scheme, the target detection by a unique, direct PL transduction is observed even in the presence of high background concentrations of interfering negatively or positively charged proteins. This mechanism is the first to selectively modulate the QD PL directly, enabling new types of label free assays and detection schemes. This direct optical transduction is possible due to oligonucleotidetemplated surface passivation and molecular recognition. This chemistry may lead to more nanoparticle-based optical and magnetic probes that can be activated in a highly chemoselective manner.
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Weber, Emanuel, Dietmar Puchberger-Enengl, and Michael J. Vellekoop. "In-Line Characterization of Micro-Droplets Based on Partial Light Reflection at the Solid-Liquid Interface." In ASME 2012 10th International Conference on Nanochannels, Microchannels, and Minichannels collocated with the ASME 2012 Heat Transfer Summer Conference and the ASME 2012 Fluids Engineering Division Summer Meeting. American Society of Mechanical Engineers, 2012. http://dx.doi.org/10.1115/icnmm2012-73155.
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In this paper a novel optofluidic setup, fabricated on a single layer device for in-line droplet characterization yielding droplet-size, droplet-frequency, and optical properties with compatibility for full on-chip integration is presented. Chips were fabricated using a simple, fast, and cost effective technology. A T-junction arrangement on the device is used for droplet generation. The optical part of the setup consists of an external light source, external silicon photodetectors, integrated air micro-lenses, and an integrated waveguide. The design makes use of partial light reflection/transmission at the solid-liquid interface to count, size, and discriminate droplets based on their optical properties. When passing the interrogation point, droplets having a lower refractive index as the continuous phase result in light deflections. Both, reflected and transmitted light, are detected simultaneously. A relation of those two signals is then used for the analysis resulting in a continuously stable signal. The generated pattern is unique for different droplets and can be exploited for droplet characterization. Using this arrangement, droplets of de-ionized water (DI) were counted at frequencies of up to 320 droplets per second. In addition, information about the droplet sizes and their variations could be obtained. Finally, 5 mol/L CaCl2 and DI droplets, having different indices of refraction were examined and could clearly be discriminated based on their unique reflected and transmitted light signals. This principle can be applied for the detection of dissolved molecules in droplets as long as they influence the index of refraction. Examples could be the determination of DNA or protein content in the droplet.
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Bahou, Oumayma, Naima Belayachi, and Brahim Ismail. "Experimental Investigation of the Compatibility of Lime Coating with Insulation Straw Biocomposite." In 4th International Conference on Bio-Based Building Materials. Switzerland: Trans Tech Publications Ltd, 2022. http://dx.doi.org/10.4028/www.scientific.net/cta.1.164.
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The use of bio-based composite as building materials is one of the innovative solutions for dealing with environmental disorders caused by the construction sector. Among these materials we find biocomposites based on vegetable aggregates, which have proven their effectiveness as insulating materials in numerous studies. Despite the growing interest in these materials and the recognition of their performance, their use remains hampered by the lack of implementation rules specific to these materials to move towards a control of their use and their durability affected by the climate and use conditions to which they will be exposed at the level of a building. The objective of this work is to study the compatibility of a protective coating with a block substrate of biocomposites based on cereal straw. It is in fact a mixture of vegetable aggregates (straw), a binder composed of lime and additives also obtained from a renewable source (Ismail et al., 2020). These additives (air-entraining agent, casein protein and a biopolymer) have been added to improve both the fibre-binder interface and the porosity of the binder. The use of these bio-based materials for external or internal thermal insulation of the building requires the application of a coating to protect them against climatic aggressions and to give them an aesthetic appearance. The lime-based coatings, air-entraining agent and casein protein selected for this study have been the subject of an experimental investigation (Brahim Ismail, 2020). In order to assess the compatibility of these coatings with the straw-based insulating material, we were interested in studying the adhesion between the biocomposite and the coating after aging cycles in accordance with the EN 1015-21 standard. The samples (biocomposite + coating) were subjected to two types of aging, one using water and the other using a saline solution of sodium sulphates (Na2SO4). The results of the bond tests after aging showed that the cohesive fracture (at the level of the substrate) is a pattern observed in all the studied systems. In Addition, It has been found that the coating to which a percentage of fine fibers has been added undergoes considerable degradation after aging with salt solution, demonstrating the need of an additional layer of outer coating without fibers in order to ensure the sustainability of the system.