1
|
Smolentsev N, Roke S. Self-Assembly at Water Nanodroplet Interfaces Quantified with Nonlinear Light Scattering. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2020; 36:9317-9322. [PMID: 32654491 DOI: 10.1021/acs.langmuir.0c01887] [Citation(s) in RCA: 9] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/27/2023]
Abstract
The interfaces of water micro- and nanodroplets drive environmental, medical, catalytic, biological, and chemical biphasic processes. The interfacial droplet structure and electrostatics greatly determine the reactivity and efficiency of these processes. Droplet interfacial properties are elusive and generally inferred from bulk measurements and are therefore anything but exact. Here, we quantify the interfacial ordering of water and the electrostatic surface potential of nanoscale water droplets in an apolar liquid using angle-resolved polarimetric second-harmonic scattering. We also present a method to determine the amount of free charges in the hydrophobic phase, reaching a sensitivity that is 3 orders of magnitude better than conductivity measurements. Investigating the structural and surface electrostatic changes induced by AOT surfactant adsorption, we find that both the hydrogen bonding as well as the electrostatics strongly depend on the surfactant concentration. Above the critical micelle concentration, the interface mediates micelle self-assembly.
Collapse
Affiliation(s)
- N Smolentsev
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| | - S Roke
- Laboratory for Fundamental BioPhotonics (LBP), Institute of Bioengineering (IBI), and Institute of Materials Science (IMX), School of Engineering (STI), and Lausanne Centre for Ultrafast Science (LACUS), École Polytechnique Fédérale de Lausanne (EPFL), CH-1015 Lausanne, Switzerland
| |
Collapse
|
2
|
Pandey R, Prabhu AA, Dasu VV. Purification of recombinant human interferon gamma from fermentation broth using reverse micellar extraction: A process optimization study. SEP SCI TECHNOL 2017. [DOI: 10.1080/01496395.2017.1395463] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Rajat Pandey
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati India
| | - Ashish Anand Prabhu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati India
| | - Veeranki Venkata Dasu
- Department of Biosciences and Bioengineering, Indian Institute of Technology Guwahati, Guwahati India
| |
Collapse
|
3
|
Park KM, Lee JH, Hong SC, Kwon CW, Jo M, Choi SJ, Kim K, Chang PS. Selective production of 1-monocaprin by porcine liver carboxylesterase-catalyzed esterification: Its enzyme kinetics and catalytic performance. Enzyme Microb Technol 2015; 82:51-57. [PMID: 26672448 DOI: 10.1016/j.enzmictec.2015.08.014] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/17/2015] [Revised: 08/04/2015] [Accepted: 08/21/2015] [Indexed: 10/23/2022]
Abstract
Porcine liver carboxylesterase (PLE) belongs to carboxylesterase family (EC 3.1.1.1) as a serine-type esterase. The PLE-catalyzed esterification of capric acid with glycerol in reverse micelles was investigated on the catalytic performance and enzyme kinetics. The most suitable structure of reverse micelles was comprised of isooctane (reaction medium) and bis(2-ethylhexyl) sodium sulfosuccinate (AOT, anionic surfactant) with 0.1 of R-value ([water]/[surfactant]) and 3.0 of G/F-value ([glycerol]/[fatty acid]) for the PLE-catalyzed esterification. In the aspect of regio-selectivity, the PLE mainly produced 1-monocaprin without any other products (di- and/or tricaprins of subsequent reactions). Furthermore, the degree of esterification at equilibrium state (after 4 h from the initiation) was 62.7% under the optimum conditions at pH 7.0 and 60 °C. Based on Hanes-Woolf plot, the apparent Km and Vmax values were calculated to be 16.44 mM and 38.91 μM/min/mg protein, respectively.
Collapse
Affiliation(s)
- Kyung-Min Park
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
| | - Jong-Hyuk Lee
- Research Institute of Food and Biotechnology, SPC group, Seoul 137-887, Republic of Korea
| | - Sung-Chul Hong
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
| | - Chang Woo Kwon
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
| | - Minje Jo
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea
| | - Seung Jun Choi
- Department of Food Science and Technology, and Department of Interdisciplinary Bio IT Materials, Seoul National University of Science and Technology, Seoul 139-743, Republic of Korea
| | - Keesung Kim
- Institute of Advanced Machinery and Design, School of Mechanical and Aerospace Engineering, Seoul National University, Seoul 151-742, Republic of Korea
| | - Pahn-Shick Chang
- Department of Agricultural Biotechnology, Seoul National University, Seoul 151-921, Republic of Korea; Center for Food and Bioconvergence, and Research Institute of Agriculture and Life Sciences, Seoul National University, Seoul 151-742, Republic of Korea.
| |
Collapse
|
4
|
Patil AJ, Li M, Mann S. Integrative self-assembly of functional hybrid nanoconstructs by inorganic wrapping of single biomolecules, biomolecule arrays and organic supramolecular assemblies. NANOSCALE 2013; 5:7161-7174. [PMID: 23824335 DOI: 10.1039/c3nr02796a] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/02/2023]
Abstract
Synthesis of functional hybrid nanoscale objects has been a core focus of the rapidly progressing field of nanomaterials science. In particular, there has been significant interest in the integration of evolutionally optimized biological systems such as proteins, DNA, virus particles and cells with functional inorganic building blocks to construct mesoscopic architectures and nanostructured materials. However, in many cases the fragile nature of the biomolecules seriously constrains their potential applications. As a consequence, there is an on-going quest for the development of novel strategies to modulate the thermal and chemical stabilities, and performance of biomolecules under adverse conditions. This feature article highlights new methods of "inorganic molecular wrapping" of single or multiple protein molecules, individual double-stranded DNA helices, lipid bilayer vesicles and self-assembled organic dye superstructures using inorganic building blocks to produce bio-inorganic nanoconstructs with core-shell type structures. We show that spatial isolation of the functional biological nanostructures as "armour-plated" enzyme molecules or polynucleotide strands not only maintains their intact structure and biochemical properties, but also enables the fabrication of novel hybrid nanomaterials for potential applications in diverse areas of bionanotechnology.
Collapse
Affiliation(s)
- Avinash J Patil
- Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Cantocks Close, BS8 1TS, UK.
| | | | | |
Collapse
|
5
|
Sapsford KE, Algar WR, Berti L, Gemmill KB, Casey BJ, Oh E, Stewart MH, Medintz IL. Functionalizing nanoparticles with biological molecules: developing chemistries that facilitate nanotechnology. Chem Rev 2013; 113:1904-2074. [PMID: 23432378 DOI: 10.1021/cr300143v] [Citation(s) in RCA: 818] [Impact Index Per Article: 74.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/06/2023]
Affiliation(s)
- Kim E Sapsford
- Division of Biology, Department of Chemistry and Materials Science, Office of Science and Engineering Laboratories, U.S. Food and Drug Administration, Silver Spring, Maryland 20993, United States
| | | | | | | | | | | | | | | |
Collapse
|
6
|
One-step separation of β-galactosidase from β-lactoglobulin using water-in-oil microemulsions. Food Chem 2012; 132:326-32. [DOI: 10.1016/j.foodchem.2011.10.085] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/17/2011] [Revised: 08/15/2011] [Accepted: 10/06/2011] [Indexed: 11/19/2022]
|
7
|
Moutinho CG, Matos CM, Teixeira JA, Balcão VM. Nanocarrier possibilities for functional targeting of bioactive peptides and proteins: state-of-the-art. J Drug Target 2011; 20:114-41. [PMID: 22023555 DOI: 10.3109/1061186x.2011.628397] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/18/2022]
Abstract
This review attempts to provide an updated compilation of studies reported in the literature pertaining to production of nanocarriers encasing peptides and/or proteins, in a way that helps the reader direct a bibliographic search and develop an integrated perspective of the subject. Highlights are given to bioactive proteins and peptides, with a special focus on those from dairy sources (including physicochemical characteristics and properties, and biopharmaceutical application possibilities of e.g. lactoferrin and glycomacropeptide), as well as to nanocarrier functional targeting. Features associated with micro- and (multiple) nanoemulsions, micellar systems, liposomes and solid lipid nanoparticles, together with biopharmaceutical considerations, are presented in the text in a systematic fashion.
Collapse
Affiliation(s)
- Carla G Moutinho
- Bioengineering and Biopharmaceutical Chemistry Research Group, Faculty of Health Sciences, Fernando Pessoa University, Porto, Portugal
| | | | | | | |
Collapse
|
8
|
Günther SL, Stuckey DC. Extraction of IgG4 Fab Fragments Using HDEHP-Isooctane and -Corn Oil Reverse Micelles. SEP SCI TECHNOL 2011. [DOI: 10.1080/01496395.2010.535236] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
9
|
Günther SL, Stuckey DC. Extraction of Human IgG4 Monoclonal Antibodies Using AOT- and HDEHP-Isooctane Reverse Micelles. SEP SCI TECHNOL 2010. [DOI: 10.1080/01496395.2010.486389] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
|
10
|
Lambert EM, Viravaidya C, Li M, Mann S. Microemulsion-mediated self-assembly and silicification of mesostructured ferritin nanocrystals. Angew Chem Int Ed Engl 2010; 49:4100-3. [PMID: 20425877 DOI: 10.1002/anie.201001043] [Citation(s) in RCA: 18] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022]
Affiliation(s)
- Elizabeth M Lambert
- Centre for Organized Matter Chemistry, School of Chemistry, University of Bristol, Bristol, BS8 1TS, UK
| | | | | | | |
Collapse
|
11
|
George DA, Stuckey DC. Extraction of monoclonal antibodies (IgG1) using anionic and anionic/nonionic reverse micelles. Biotechnol Prog 2010; 26:1352-60. [DOI: 10.1002/btpr.453] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
|
12
|
Lambert E, Viravaidya C, Li M, Mann S. Microemulsion-Mediated Self-Assembly and Silicification of Mesostructured Ferritin Nanocrystals. Angew Chem Int Ed Engl 2010. [DOI: 10.1002/ange.201001043] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/13/2023]
|
13
|
Characterization and optimization of carboxylesterase-catalyzed esterification between capric acid and glycerol for the production of 1-monocaprin in reversed micellar system. N Biotechnol 2010; 27:46-52. [DOI: 10.1016/j.nbt.2009.11.004] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2009] [Revised: 11/02/2009] [Accepted: 11/10/2009] [Indexed: 11/18/2022]
|
14
|
Nandini K, Rastogi NK. Reverse micellar extraction for downstream processing of lipase: Effect of various parameters on extraction. Process Biochem 2009. [DOI: 10.1016/j.procbio.2009.06.020] [Citation(s) in RCA: 50] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
|
15
|
Martínez-Aragón M, Goetheer E, de Haan A. Host–guest extraction of immunoglobulin G using calix[6]arenas. Sep Purif Technol 2009. [DOI: 10.1016/j.seppur.2008.03.017] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/15/2022]
|
16
|
Kim JY, Dungan SR. Effect of α-Lactalbumin on Aerosol-OT Phase Structures in Oil/Water Mixtures. J Phys Chem B 2008; 112:5381-92. [DOI: 10.1021/jp7112413] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Jun Y. Kim
- Department of Food Science and Technology, Department of Chemical Engineering and Materials Science, University of California, Davis, One Shields Avenue, Davis, California 95616
| | - Stephanie R. Dungan
- Department of Food Science and Technology, Department of Chemical Engineering and Materials Science, University of California, Davis, One Shields Avenue, Davis, California 95616
| |
Collapse
|
17
|
RAWAT M, SINGH D, SARAF S, SARAF S. Lipid Carriers: A Versatile Delivery Vehicle for Proteins and Peptides. YAKUGAKU ZASSHI 2008; 128:269-80. [DOI: 10.1248/yakushi.128.269] [Citation(s) in RCA: 78] [Impact Index Per Article: 4.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
Affiliation(s)
- Manju RAWAT
- Institute of Pharmacy, Pt Ravishankar Shukla University
| | | | - S. SARAF
- Institute of Pharmacy, Pt Ravishankar Shukla University
| | | |
Collapse
|
18
|
Carballido-Landeira J, Berenstein I, Taboada P, Mosquera V, Vanag VK, Epstein IR, Pérez-Villar V, Muñuzuri AP. Long-lasting dashed waves in a reactive microemulsion. Phys Chem Chem Phys 2008; 10:1094-6. [DOI: 10.1039/b714705h] [Citation(s) in RCA: 13] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
|
19
|
Abstract
Microemulsions are thermodynamically stable, transparent, low viscosity, and isotropic dispersions consisting of oil and water stabilized by an interfacial film of surfactant molecules, typically in conjunction with a cosurfactant. Microemulsions (so-called due to their small particle size; 5-100 nm) have found application in a wide variety of systems, such as pharmaceutical and oil recovery, but their application in food systems has been hindered by the types of surfactant permissible for use in food. The objective of this review is to provide an overview of the structures and phase behavior of microemulsions, methods of microemulsion formation, and techniques which may be used for characterization. A comprehensive review of previous work on both food-grade microemulsion systems, and non-food-grade systems of specific food interest is included. The application of microemulsions as reaction media, their ability to solubilize proteins and hence their use as a separation technique is also documented. In addition, attention is focused on the application of microemulsions as delivery systems for delivery of bioactive compounds, and the links between microemulsions and increased bioavailability. Future research, both applied and fundamental, should focus on surfactants which are not restricted for use in foods.
Collapse
Affiliation(s)
- John Flanagan
- Riddet Centre, Massey University, Palmerston North, New Zealand. j.flanagan@ massey.ac.nz
| | | |
Collapse
|
20
|
Simorellis AK, Van Horn WD, Flynn PF. Dynamics of Low Temperature Induced Water Shedding from AOT Reverse Micelles. J Am Chem Soc 2006; 128:5082-90. [PMID: 16608342 DOI: 10.1021/ja0568401] [Citation(s) in RCA: 31] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
The effects of low temperature and ionic strength on water encapsulated within reverse micelles were investigated by solution NMR. Reverse micelles composed of AOT and pentane and solutions with varying concentrations of NaCl were studied at temperatures ranging from 20 degrees C to -30 degrees C. One-dimensional (1)H solution NMR spectroscopy was used to monitor the quantity and structure of encapsulated water. At low temperatures, e.g., -30 degrees C, reverse micelles lose water at rates that are dependent on the ionic strength of the aqueous nanopool. The final water loading (w0 = [water]/[surfactant]) of the reverse micelles is likewise dependent on the ionic strength of the aqueous phase. Remarkably, water resonance(s) at temperatures between -20 degrees C and -30 degrees C displayed fine structure indicating the presence of multiple transient water populations. Results of this study demonstrate that reverse micelles are an excellent vehicle for studies of confined water across a broad range of conditions, including the temperature range that provides access to the supercooled state.
Collapse
Affiliation(s)
- Alana K Simorellis
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA
| | | | | |
Collapse
|
21
|
Feng X, Zhang J, Chen J, Han B, Shen D. Enhanced Solubilization of Bovine Serum Albumin in Reverse Micelles by Compressed CO2. Chemistry 2006; 12:2087-93. [PMID: 16358346 DOI: 10.1002/chem.200500812] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The effect of compressed CO2 on the solubilization of bovine serum albumin (BSA) in water/sodium bis-(2-ethylhexyl) sulfosuccinate (AOT)/isooctane reverse micelles was studied by observing phase behavior and recording UV-visible spectra under different conditions. The pH values within the water cores of reverse micelles at different CO2 pressures were also determined. The solubilization capacity of the reverse micelles for the protein increased considerably as CO2 pressure increased within the low-pressure range, but decreased at higher CO2 pressures, so that the micelles eventually lost their ability to solubilize the protein. The effect of CO2 on the stability of the reverse micelles played an important role in the relationship between pressure and protein solubility. A "multicomplex" model was proposed to explain these effects. The different solublization capacities within different pressure ranges demonstrates the unique advantage of using compressed CO2 in the extraction of proteins with reverse micelles.
Collapse
Affiliation(s)
- Xiaoying Feng
- The Center for Molecular Sciences, Institute of Chemistry, Chinese Academy of Sciences, Beijing 100080 (China)
| | | | | | | | | |
Collapse
|
22
|
Abstract
Water-soluble proteins encapsulated within reverse micelles may be studied under a variety of conditions, including low temperature and a wide range of buffer conditions. Direct high-resolution detection of information relating to protein folding intermediates and pathways can be monitored by low-temperature solution NMR. Ubiquitin encapsulated within AOT reverse micelles was studied using multidimensional multinuclear solution NMR to determine the relationship between protein structure, temperature, and ionic strength. Ubiquitin resonances were monitored by 15N HSQC NMR experiments at varying temperatures and salt concentrations. Our results indicate that the structure of the encapsulated protein at low temperature experiences perturbation arising from two major influences, which are reverse micelle-protein interactions and low-temperature effects (e.g., cold denaturation). These two effects are impossible to distinguish under conditions of low ionic strength. Elevated concentrations of nondenaturing salt solutions defeat the effects of reverse micelle-protein interactions and reveal low-temperature protein unfolding. High ionic strength shielding stabilizes the reverse micelle at low temperatures, which reduces the electrostatic interaction between the protein and reverse micelle surfaces, allowing the phenomenon of cold denaturation to be explored.
Collapse
Affiliation(s)
- Wade D Van Horn
- Department of Chemistry, University of Utah, Salt Lake City, Utah 84112-0850, USA
| | | | | |
Collapse
|
23
|
Shimek JW, Rohloff CM, Goldberg J, Dungan SR. Effect of alpha-lactalbumin on the phase behavior of AOT-brine-isooctane mixtures: role of charge interactions. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2005; 21:5931-9. [PMID: 15952844 DOI: 10.1021/la047464l] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
We have found that both electrostatic and hydrophobic interactions are involved in the ability of the protein alpha-lactalbumin (alpha-LA) to affect the self-assembly of the anionic surfactant sodium bis(ethylhexyl) sulfosuccinate (AOT, 3.5 wt %) in equivolume mixtures of organic and aqueous solutions. The composition and size of AOT phase structures that form in the presence of 0.35 wt % protein were evaluated as a function of pH and ionic strength. In the absence of protein, AOT forms water-in-oil microemulsion droplets for all pH and salt concentrations studied here. The presence of the protein in the water-in-oil microemulsion phase boosts water solubilization and droplet size, as the spontaneous curvature of the surfactant interface becomes less negative. Aggregates of protein, surfactant, and oil also form in the water-continuous phase. The size and composition of structures in both phases can be tuned in the presence of protein by varying the pH and ionic strength. alpha-LA induces the appearance of an anisotropic surfactant phase at pH <5.8. At intermediate salt concentrations, a third isotropic, viscous aqueous phase appears that contains 55-60% of the protein, 10-14% of the surfactant, and significant amounts of oil. Circular dichroism and fluorescence spectroscopy indicate that the protein contains enhanced alpha-helical secondary structure when self-assembling with surfactant, and has a loosened tertiary structure. The protein does not interact with the surfactant as an unfolded random coil. Although the conformation of alpha-LA in aqueous salt solutions is known to depend on pH, when self-assembling with AOT the protein adopts a structure whose features are quite pH insensitive, and likely reflect an intrinsic interaction with the interface.
Collapse
Affiliation(s)
- Justin W Shimek
- Department of Chemical Engineering and Materials Science, University of California, One Shields Avenue, Davis, California 95616, USA
| | | | | | | |
Collapse
|
24
|
Gerhardt NI, Dungan SR. Changes in Microemulsion and Protein Structure in IgG−AOT−Brine−Isooctane Systems. J Phys Chem B 2004. [DOI: 10.1021/jp040231i] [Citation(s) in RCA: 11] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Natalia I. Gerhardt
- Department of Food Science and Technology and Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616
| | - Stephanie R. Dungan
- Department of Food Science and Technology and Department of Chemical Engineering and Materials Science, University of California, Davis, California 95616
| |
Collapse
|
25
|
Rohloff CM, Shimek JW, Dungan SR. Effect of added α-lactalbumin protein on the phase behavior of AOT–brine–isooctane systems. J Colloid Interface Sci 2003; 261:514-23. [PMID: 16256563 DOI: 10.1016/s0021-9797(03)00079-1] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2002] [Accepted: 01/14/2003] [Indexed: 10/27/2022]
Abstract
We have found that the presence of <1 wt% of the globular protein alpha-lactalbumin has a significant impact on the equilibrium phase behavior of dilute sodium bis(ethylhexyl) sulfosuccinate (AOT)/brine/isooctane systems. Nuclear magnetic resonance (NMR), Karl Fischer titration, and ultraviolet spectroscopy were used to determine the surfactant, oil, water, and protein content of the organic and aqueous phases as a function of the total surfactant and protein present. As a small amount of alpha-lactalbumin is added to the mixture, there is a substantial increase (up to 80%) in the maximum water solubility in the water-in-oil microemulsion phase. Dynamic light scattering measurements indicate that this increase is due to a decrease in the magnitude of the (negative) spontaneous curvature of the surfactant monolayer, as droplets swell in size. As the molar ratio of alpha-lactalbumin to AOT surpasses approximately 1:300, the partitioning of water, protein, and surfactant shifts to the excess aqueous phase, where soluble assemblies with positive curvature are detected by dynamic light scattering. Significant amounts of isooctane are solubilized in these aggregates, consistent with the formation of oil-in-water microemulsion droplets. Circular dichroism studies showed that the tertiary structure of the protein in the microemulsion is disrupted while the secondary structure is increased. In light of these findings, the protein most likely expands to a molten-globule type conformation in the AOT interfacial environment, but does not substantially unfold to become an extended chain.
Collapse
Affiliation(s)
- Catherine M Rohloff
- Department of Chemical Engineering and Materials Science, University of California, Davis, CA 95616, USA
| | | | | |
Collapse
|
26
|
Abstract
Separation of immunoglobulin G (IgG) from the other colostral whey proteins was carried out by reversed micellar extraction. The colostral whey was diluted to 5 times its original volume with 50 mM phosphate buffer at pH 6.35 containing 100 mM of sodium chloride. The aqueous solution was then mixed with an equal volume of isooctane containing 50 mM bis-(2-ethylhexyl) sodium sulfosuccinate (AOT), and shaken at 200 rpm and 25 degrees C for 10 min. After extraction, the mixture was separated to the aqueous phase and the reversed micellar phase by centrifugation. This procedure extracted most of the non-IgG proteins to the reversed micellar phase and recovered more than 90% of the IgG in the aqueous phase. The IgG in the aqueous phase had a purity of 90%, and still possessed immunological activity. AOT was not detectable in the aqueous phase.
Collapse
Affiliation(s)
- Chia-Kai Su
- Department of Leisure, Recreation, and Tourism Management, Southern Taiwan University of Technology, Tainan, Taiwan, Republic of China
| | | |
Collapse
|