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Alfonso C, Sobrinos-Sanguino M, Luque-Ortega JR, Zorrilla S, Monterroso B, Nuero OM, Rivas G. Studying Macromolecular Interactions of Cellular Machines by the Combined Use of Analytical Ultracentrifugation, Light Scattering, and Fluorescence Spectroscopy Methods. ADVANCES IN EXPERIMENTAL MEDICINE AND BIOLOGY 2024; 3234:89-107. [PMID: 38507202 DOI: 10.1007/978-3-031-52193-5_7] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/22/2024]
Abstract
Cellular machines formed by the interaction and assembly of macromolecules are essential in many processes of the living cell. These assemblies involve homo- and hetero-associations, including protein-protein, protein-DNA, protein-RNA, and protein-polysaccharide associations, most of which are reversible. This chapter describes the use of analytical ultracentrifugation, light scattering, and fluorescence-based methods, well-established biophysical techniques, to characterize interactions leading to the formation of macromolecular complexes and their modulation in response to specific or unspecific factors. We also illustrate, with several examples taken from studies on bacterial processes, the advantages of the combined use of subsets of these techniques as orthogonal analytical methods to analyze protein oligomerization and polymerization, interactions with ligands, hetero-associations involving membrane proteins, and protein-nucleic acid complexes.
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Affiliation(s)
- Carlos Alfonso
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain.
| | - Marta Sobrinos-Sanguino
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Juan Román Luque-Ortega
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Silvia Zorrilla
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Begoña Monterroso
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Oscar M Nuero
- Molecular Interactions Facility, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
| | - Germán Rivas
- Structural and Chemical Biology Department, Centro de Investigaciones Biológicas Margarita Salas, Consejo Superior de Investigaciones Científicas, Madrid, Spain
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Tahara U, Matsui T, Atsugi T, Fukuda K, Terooatea TW, Minoda A, Kubo A, Amagai M. Keratinocytes of the Upper Epidermis and Isthmus of Hair Follicles Express Hemoglobin mRNA and Protein. J Invest Dermatol 2023; 143:2346-2355.e10. [PMID: 37981423 DOI: 10.1016/j.jid.2023.08.008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 11/21/2023]
Abstract
The epidermis, the keratinized stratified squamous epithelium surrounding the body surface, offers a valuable framework to investigate how terrestrial animals overcome environmental stresses. However, the mechanisms underlying epidermal barrier function remain nebulous. In this study, we examined genes highly expressed in the human and mouse upper epidermis, the outer frontier that induces various barrier-related genes. Transcriptome analysis revealed that the messenger RNA level of hemoglobin α (HBA), an oxygen carrier in erythroid cells, was enriched in the upper epidermis compared with that in the whole epidermis. Immunostaining analysis confirmed HBA protein expression in human and mouse keratinocytes (KCs) of the stratum spinosum and stratum granulosum. HBA was also expressed in hair follicle KCs in the isthmus region; its expression levels were more prominent than those in interfollicular KCs. HBA expression was not observed in noncutaneous keratinized stratified squamous epithelia of mice, for example, the vagina, esophagus, and forestomach. HBA expression was upregulated in human epidermal KC cultures after UV irradiation, a major cause of skin-specific oxidative stress. Furthermore, HBA knockdown increased UV-induced production of ROS in primary KCs. Our findings suggest that epidermal HBA expression is induced by oxidative stress and acts as an antioxidant, contributing to skin barrier function.
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Affiliation(s)
- Umi Tahara
- Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
| | - Takeshi Matsui
- Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; Department of Dermatology, Keio University School of Medicine, Tokyo, Japan; Laboratory for Evolutionary Cell Biology of the Skin, School of Bioscience and Biotechnology, Tokyo University of Technology, Hachioji, Japan
| | - Toru Atsugi
- Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
| | - Keitaro Fukuda
- Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; Department of Dermatology, Keio University School of Medicine, Tokyo, Japan
| | - Tommy W Terooatea
- Laboratory for Cellular Epigenomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan
| | - Aki Minoda
- Laboratory for Cellular Epigenomics, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; Department of Cell Biology, Faculty of Science, Radboud Institute for Molecular Life Sciences, Radboud University, Nijmegen, The Netherlands
| | - Akiharu Kubo
- Department of Dermatology, Keio University School of Medicine, Tokyo, Japan; Division of Dermatology, Department of Internal Related, Kobe University Graduate School of Medicine, Kobe, Japan
| | - Masayuki Amagai
- Laboratory for Skin Homeostasis, RIKEN Center for Integrative Medical Sciences, Yokohama, Japan; Department of Dermatology, Keio University School of Medicine, Tokyo, Japan.
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Sakamoto W, Azegami N, Konuma T, Akashi S. Single-Cell Native Mass Spectrometry of Human Erythrocytes. Anal Chem 2021; 93:6583-6588. [PMID: 33871982 DOI: 10.1021/acs.analchem.1c00588] [Citation(s) in RCA: 7] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
Native mass spectrometry (MS) enables the determination of the molecular mass of protein complexes. Generally, samples for native MS are isolated, purified, and prepared in volatile solutions. However, to understand the function of proteins in living cells, it is essential to characterize the protein complex as is, without isolation/purification of the protein, using the smallest possible amount of the sample. In the present study, we modified the "live single-cell MS" method, which has mainly been used in metabolomics, and applied it to observe hemoglobin directly sampled from human erythrocytes. By optimizing the experimental methods and conditions, we obtained native mass spectra of hemoglobin using only a single erythrocyte, which was directly sampled into a nanoelectrospray ionization emitter using a micromanipulator and microinjector system. That is, our method enables the analysis of ∼0.45 fmol of hemoglobin directly sampled from an erythrocyte. To our knowledge, this is the first report of native MS for endogenous proteins using a single intact human cell.
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Matsuhira T, Kure T, Yamamoto K, Sakai H. Analysis of Dimeric αβ Subunit Exchange between PEGylated and Native Hemoglobins (α2β2 Tetramer) in an Equilibrated State by Intramolecular ββ-Cross-Linking. Biomacromolecules 2018; 19:3412-3420. [DOI: 10.1021/acs.biomac.8b00728] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Affiliation(s)
- Takashi Matsuhira
- Department of Chemistry, Nara Medical University, 840 Shijo-cho, Kashihara, 634-8521, Japan
| | - Tomoko Kure
- Department of Chemistry, Nara Medical University, 840 Shijo-cho, Kashihara, 634-8521, Japan
| | - Keizo Yamamoto
- Department of Chemistry, Nara Medical University, 840 Shijo-cho, Kashihara, 634-8521, Japan
| | - Hiromi Sakai
- Department of Chemistry, Nara Medical University, 840 Shijo-cho, Kashihara, 634-8521, Japan
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5
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Some D. Light-scattering-based analysis of biomolecular interactions. Biophys Rev 2013; 5:147-158. [PMID: 23646069 PMCID: PMC3641300 DOI: 10.1007/s12551-013-0107-1] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/26/2012] [Accepted: 01/31/2013] [Indexed: 01/06/2023] Open
Abstract
While light scattering has long been applied to the analysis of biomolecular interactions, recent advances have extended the practical use of light scattering techniques to cover a rather broad range of phenomena. In this paper I review essential light scattering theory as applied to specific interactions under thermodynamically ideal conditions and present examples showing how light scattering elucidates the dynamic equilibrium and kinetic behavior of proteins and other biomacromolecules.
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Affiliation(s)
- Daniel Some
- Wyatt Technology Corp, 6300 Hollister Ave, Santa Barbara, CA 93117 USA
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6
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Monterroso B, Alfonso C, Zorrilla S, Rivas G. Combined analytical ultracentrifugation, light scattering and fluorescence spectroscopy studies on the functional associations of the bacterial division FtsZ protein. Methods 2013; 59:349-62. [DOI: 10.1016/j.ymeth.2012.12.014] [Citation(s) in RCA: 20] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/02/2012] [Revised: 12/22/2012] [Accepted: 12/26/2012] [Indexed: 11/28/2022] Open
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7
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Kang Y, Douglas DJ. Gas-phase ions of human hemoglobin A, F, and S. JOURNAL OF THE AMERICAN SOCIETY FOR MASS SPECTROMETRY 2011; 22:1187-1196. [PMID: 21953101 DOI: 10.1007/s13361-011-0138-4] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 01/19/2011] [Revised: 03/16/2011] [Accepted: 03/18/2011] [Indexed: 05/31/2023]
Abstract
Hemoglobin (Hb) (α(2)β(2)) is a tetrameric protein-protein complex. Collision cross sections, hydrogen exchange levels, and tandem mass spectrometry have been used to investigate the properties of gas-phase monomer, dimer, and tetramer ions of adult human hemoglobin (Hb A, α(2)β(2)), and two variant hemoglobins: fetal hemoglobin (Hb F, α(2)γ(2)) and sickle hemoglobin (Hb S, α(2)β(2), E6V[β]). All three proteins give similar mass spectra. Monomers of Hb S and Hb F have similar cross sections, ca. 10% greater than those of Hb A. Cross sections of dimer ions of Hb S are 11% greater than those of Hb A and 6% greater than those of Hb F. Tetramers of Hb S are 13% larger than tetramers of Hb A or Hb F. Monomers and dimers of all three Hb have similar hydrogen-deuterium exchange (HDX) levels. Tetramers of Hb S exchange 16% more hydrogens than Hb A and Hb F. In tandem mass spectrometry, monomers of Hb S and Hb F require ca. 10% greater internal energy for heme loss than Hb A. Dimers (+11) of Hb A and Hb S dissociate to monomers with asymmetrical charge division; dimers of Hb F (+11) dissociate with nearly equal charge division. Tetramer ions dissociate to monomers and trimers, unlike solution Hb, which dissociates to dimers. The most stable dimers are from Hb S; the most stable tetramers from Hb F. The results with Hb S show that a single mutation in the β chain can change the physical properties of this gas-phase protein-protein complex.
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Affiliation(s)
- Yang Kang
- Department of Chemistry, University of British Columbia, 2036 Main Mall, Vancouver, BC, V6T 1Z1, Canada
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8
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Arisaka F, Nagai Y, Nagai M. Dimer–tetramer association equilibria of human adult hemoglobin and its mutants as observed by analytical ultracentrifugation. Methods 2011; 54:175-80. [DOI: 10.1016/j.ymeth.2011.01.003] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2010] [Revised: 01/10/2011] [Accepted: 01/13/2011] [Indexed: 10/18/2022] Open
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9
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Hanlon AD, Larkin MI, Reddick RM. Free-solution, label-free protein-protein interactions characterized by dynamic light scattering. Biophys J 2010; 98:297-304. [PMID: 20338851 DOI: 10.1016/j.bpj.2009.09.061] [Citation(s) in RCA: 66] [Impact Index Per Article: 4.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2009] [Revised: 09/21/2009] [Accepted: 09/28/2009] [Indexed: 11/26/2022] Open
Abstract
We report a free-solution, label-free method for quantitative characterization of macromolecular interactions using dynamic light scattering, a temperature controlled plate reader, and a multiwell concentration gradient. This nondestructive technique enabled determination of stoichiometry of binding, equilibrium dissociation constant, and thermodynamic parameters, as well as the impact of temperature, buffer salinity, and a small-molecule inhibitor. The low volume capability of dynamic light scattering reduced the required sample to 426 pmol/experiment, with detection limits for 150-kDa proteins anticipated to be in the low femtomole range.
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Affiliation(s)
- Amy D Hanlon
- Department of Research and Development, Wyatt Technology, Santa Barbara, California, USA.
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10
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Chen Y, Qian C, Guo C, Ge F, Zhang X, Gao X, Shen S, Lian B, Kitazato K, Wang Y, Xiong S. A Cys/Ser mutation of NDPK-A stabilizes its oligomerization state and enhances its activity. J Biochem 2010; 148:149-55. [PMID: 20403806 DOI: 10.1093/jb/mvq041] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/13/2022] Open
Abstract
Nucleoside diphosphate phosphate transferase A (NDPK-A) has been shown to play critical roles in the regulation of proliferation, differentiation, growth and apoptosis of cells. Our previous study suggested that the disulphide cross-linkage between cysteine 4 (C4) and cysteine 145 (C145) of NDPK-A might be a possible regulator of its activity. To confirm this hypothesis, the C145 residue of NDPK-A was mutated to serine, and the isomerization and biological activities of the mutant were investigated and compared with those of its wild-type counterpart. It was found the C145S mutation eliminated the intramolecular disulphide bond (DB) and prevented the formation of intermolecular DB, which was known to dissociate the hexameric NDPK-A into dimeric one. We also demonstrated that the C145S mutation didn't affect the autologous hexamerization of this protein, and the mutant had increased bioactivities including phosphate transferase and DNase. These findings support the hypothesis that the formation of DBs in NDPK-A is involved in the regulation of the oligomerization and bioactivity of this multiple function protein, and that C145 is a key residue in the regulation of NDPK-A. In addition, the C145S mutant that we have constructed might be an attractive candidate for use in applications that require NDPK-A.
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Affiliation(s)
- Yunru Chen
- Biomedical R&D Center, Guangdong Provincial Key Laboratory of Bioengineering Medicine, National Engineering Research Center of Genetic Medicine, Jinan University, Guangzhou, Guangdong, P. R. China 510632
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11
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Li X, Zhang X, Liu Q. Determination of the Molecular Weight Distribution of the PEGylated Bovine Hemoglobin (PEG-bHb). ACTA ACUST UNITED AC 2009; 33:13-25. [PMID: 15768562 DOI: 10.1081/bio-200046639] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
The method to determine the average molecular weight and distribution of molecular weight of the PEGylated hemoglobin (PEG-bHb) and their molecular weight of polypeptides in PEG-bHb with UV absorbance (UV), light scattering (LS) and refractive index (RI) detectors is described in this paper. The results indicate that when molar ratio of PEG to hemoglobin is 7:1, the average molecular weight of PEG-bHb (M(CP) is 95 kDa, the average molecular weigh of protein moiety in PEG-bHb (M(P)) is 68 kDa, and their distribution is from 48-157 kDa and 44-121 kDa, respectively; when the molar ratio is 10:1, the M(CP) is 106 kDa, the M(P) is 70kDa, and their distribution is from 56-216kDa, 49-135kDa, respectively; when the molar ratio is 13:1, the M(CP) is 73kDa, and their distribution is from 81-272 kDa and 41-144 kDa, respectively. It has been proved that this method is a simple and reliable way for the determination of average molecular weight and distribution of molecular weight of PEGlyted hemoglobin. This experiment also suggests that there exists not only aggregation in the frontal of elution peak of PEG-bHb, but dissociation of tetramer of hemoglobin into dimmer in the tail of elution peak, and the degree of aggregation is depended on the molar ratio of PEG to hemoglobin due to the present of diol PEG and the dissociation is dependant on the concentration of hemoglobin.
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Affiliation(s)
- Xianzhong Li
- Beijing Kaizheng Biotech Developing Ltd, Beijing, PR China
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12
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Purdy JG, Flanagan JM, Ropson IJ, Craven RC. Retroviral capsid assembly: a role for the CA dimer in initiation. J Mol Biol 2009; 389:438-51. [PMID: 19361521 DOI: 10.1016/j.jmb.2009.04.006] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2009] [Revised: 03/31/2009] [Accepted: 04/02/2009] [Indexed: 12/24/2022]
Abstract
In maturing retroviral virions, CA protein assembles to form a capsid shell that is essential for infectivity. The structure of the two folded domains [N-terminal domain (NTD) and C-terminal domain (CTD)] of CA is highly conserved among various retroviruses, and the capsid assembly pathway, although poorly understood, is thought to be conserved as well. In vitro assembly reactions with purified CA proteins of the Rous sarcoma virus (RSV) were used to define factors that influence the kinetics of capsid assembly and provide insights into underlying mechanisms. CA multimerization was triggered by multivalent anions providing evidence that in vitro assembly is an electrostatically controlled process. In the case of RSV, in vitro assembly was a well-behaved nucleation-driven process that led to the formation of structures with morphologies similar to those found in virions. Isolated RSV dimers, when mixed with monomeric protein, acted as efficient seeds for assembly, eliminating the lag phase characteristic of a monomer-only reaction. This demonstrates for the first time the purification of an intermediate on the assembly pathway. Differences in the intrinsic tryptophan fluorescence of monomeric protein and the assembly-competent dimer fraction suggest the involvement of the NTD in the formation of the functional dimer. Furthermore, in vitro analysis of well-characterized CTD mutants provides evidence for assembly dependence on the second domain and suggests that the establishment of an NTD-CTD interface is a critical step in capsid assembly initiation. Overall, the data provide clear support for a model whereby capsid assembly within the maturing virion is dependent on the formation of a specific nucleating complex that involves a CA dimer and is directed by additional virion constituents.
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Affiliation(s)
- John G Purdy
- Department of Microbiology and Immunology, College of Medicine, The Pennsylvania State University, 500 University Drive, Hershey, PA 17033, USA
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13
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Xu L, Glatz CE. Predicting protein retention time in ion-exchange chromatography based on three-dimensional protein characterization. J Chromatogr A 2009; 1216:274-80. [DOI: 10.1016/j.chroma.2008.11.075] [Citation(s) in RCA: 21] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/17/2008] [Revised: 11/21/2008] [Accepted: 11/26/2008] [Indexed: 11/26/2022]
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14
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Liu T, Guo R. Effects of Triton X-100 and Acyclovir on Human Serum Albumin Structure. J SURFACTANTS DETERG 2007. [DOI: 10.1007/s11743-007-1051-5] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/22/2022]
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15
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Influences of Triton X-100 micelle on the microstructure of HSA. Colloid Polym Sci 2006. [DOI: 10.1007/s00396-006-1528-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/24/2022]
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16
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Attri AK, Minton AP. New methods for measuring macromolecular interactions in solution via static light scattering: basic methodology and application to nonassociating and self-associating proteins. Anal Biochem 2005; 337:103-10. [PMID: 15649382 DOI: 10.1016/j.ab.2004.09.045] [Citation(s) in RCA: 54] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2004] [Indexed: 10/26/2022]
Abstract
A method for rapid detection and characterization of reversible associations of macromolecules in solution is presented. A programmable dual-syringe infusion pump is used to introduce a solution of time-varying composition into parallel flow cells for concurrent measurement of laser light scattering at multiple angles and ultraviolet-visible absorbance. An experiment lasting less than 15 min produces a large and information-rich set of data, consisting of several thousand values of the Rayleigh ratio as a function of solute concentration(s) and scattering angle. Using a novel treatment of the data, the entire data set may be equally rapidly analyzed in the context of models for self-association. Validation experiments conducted on previously characterized nonassociating and self-associating proteins yielded robust values for molecular weights in the range 10-330 kDa and equilibrium association constants for dimer formation in the range 2 x 10(3)-6 x 10(5) M(-1).
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Affiliation(s)
- Arun K Attri
- Section on Physical Biochemistry, Laboratory of Biochemistry and Genetics, National Institute of Diabetes and Digestive and Kidney Diseases, National Institutes of Health, U.S. Department of Health and Human Services, Bethesda, MD 20892, USA
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Sinha S, Surolia A. Oligomerization endows enormous stability to soybean agglutinin: a comparison of the stability of monomer and tetramer of soybean agglutinin. Biophys J 2005; 88:4243-51. [PMID: 15792973 PMCID: PMC1305654 DOI: 10.1529/biophysj.105.061309] [Citation(s) in RCA: 33] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/14/2005] [Accepted: 03/18/2005] [Indexed: 11/18/2022] Open
Abstract
Soybean agglutinin is a tetrameric legume lectin, each of whose subunits are glycosylated. This protein shows a very high degree of stability when compared to the other proteins of the same family. In a previous work, it was shown that the unusual stability of the protein is due to a high degree of subunit interactions. In this study we present the thermodynamic parameters for the stability of soybean agglutinin monomer. The monomeric species is found at pH 2 and below which it is most populated at pH 1.9, as evident from size-exclusion chromatographic and dynamic light scattering studies. The analyses of circular dichroism and fluorescence spectroscopy suggest that the monomer is well folded, and that it has certain characteristic features when compared to its tetrameric counterpart. The conformational stabilities of the tetramer and the monomer at the temperature of their maximum stabilities (310 K) are 59.2 kcal/mol and 9.8 kcal/mol, respectively, indicating that oligomerization contributes significantly to the stability of the native molecule. Also, the T(g) difference for the two forms of the protein is approximately 40 K, whereas the difference in DeltaC(p) is only 1.6 kcal/mol/K. This suggests that the major hydrophobic core is present in the monomer itself, and that oligomerization involves mainly ionic interactions.
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Affiliation(s)
- Sharmistha Sinha
- Molecular Biophysics Unit, Indian Institute of Science, Bangalore
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18
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Casini GL, Graham D, Heine D, Garcea RL, Wu DT. In vitro papillomavirus capsid assembly analyzed by light scattering. Virology 2004; 325:320-7. [PMID: 15246271 DOI: 10.1016/j.virol.2004.04.034] [Citation(s) in RCA: 101] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2004] [Revised: 03/24/2004] [Accepted: 04/13/2004] [Indexed: 11/27/2022]
Abstract
Pentamers of the L1 major capsid protein of human papillomavirus (HPV type 11) were purified after expression in E. coli and analyzed for the kinetics of in vitro capsid self-assembly using multi-angle light scattering (MALS). Pentamers self-assembled into capsid-like structures at a rate that was a function of protein concentration. The kinetics of capsid formation were sigmoidal with a concentration-dependent lag phase, followed by a rapid increase in polymerization. Nucleation size and the rate order of subsequent subunit addition were calculated from the concentration dependence of the extent of capsid formation and the rate of the fast phase, respectively. Assembly was second order with a nucleation size of two pentamers. Thus, we suggest that dimers of pentamers are the nucleus for L1 assembly into capsid-like structures, with rapid sequential addition of single pentamers to the growing shell. Although studied in vitro without accessory factors that may be present in vivo, these data are in contrast with the "five-around-one" assembly nucleus previously proposed for polyomaviruses.
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Affiliation(s)
- Greg L Casini
- Section of Pediatric Hematology/Oncology, University of Colorado School of Medicine, Denver, CO 80262, USA
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Lu L, Wang X, Xian M, Liu Q. Study of bovine hemoglobin dissociation by multiangle laser light-scattering method. ACTA ACUST UNITED AC 2004; 32:229-41. [PMID: 15274430 DOI: 10.1081/bio-120037829] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/03/2022]
Abstract
Hemoglobin (Hb) is an oligomeric protein, composed of four monomeric subunits. Hb molecule may undergo dissociation from a single native tetramer to two dimmers, which is called hemoglobin dissociation. In this article the dissociation of bovine Hb is studied by measurment of the average MW of the samples using the multiangle laser light-scattering method. Advanced multiangle laser light-scattering technique is a powerful method to determine the absolute molecular weights of the protein in solution. Two different methods, microbatch multiangle light-scattering (MALS) and on-line size-exclusion high-performance liquid chromatography light scattering with refractive index detector, are used to measure the average molecular weight of bovine Hb in different concentration respectively. The results of the two methods are agreed well. From the results, it can be concluded that the average molecular weigh of bovine Hb will be about 54 kDa when the bovine Hb concentration is more than 1.5 mg/mL, and will be about 36 kDa when the concentration is less than 0.03 mg/mL. The other conclusion, which can be derived from these results, is that the dissociation of bovine Hb is related with the pH and the tetramer appears to be more stable in the pH range of 6-9.
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Affiliation(s)
- Lu Lu
- Beijing Kaizheng Biotech Developing Ltd., Beijing, PR China
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