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Development of a d-amino acids electrochemical sensor based on immobilization of thermostable d-Proline dehydrogenase within agar gel membrane. Anal Chim Acta 2008; 619:215-20. [DOI: 10.1016/j.aca.2008.04.063] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/05/2008] [Revised: 04/26/2008] [Accepted: 04/29/2008] [Indexed: 11/19/2022]
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Boral S, Saxena A, Bohidar HB. Universal Growth of Microdomains and Gelation Transition in Agar Hydrogels. J Phys Chem B 2008; 112:3625-32. [DOI: 10.1021/jp7101463] [Citation(s) in RCA: 29] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- Shilpi Boral
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - Anita Saxena
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
| | - H. B. Bohidar
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
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Gupta AN, Bohidar HB, Aswal VK. Surface patch binding induced intermolecular complexation and phase separation in aqueous solutions of similarly charged gelatin-chitosan molecules. J Phys Chem B 2007; 111:10137-45. [PMID: 17676887 DOI: 10.1021/jp070745s] [Citation(s) in RCA: 47] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The formation of selective surface patch binding induced complex coacervates between polyions, chitosan (cationic polyelectrolyte), and alkali-processed gelatin (polyampholyte), both carrying similar net charge, was investigated for two volumetric mixing ratios: r = [chitosan]/[gelatin] = 1:5 and 1:10. Formation of soluble intermolecular complexes between gelatin and chitosan molecules was observed in a narrow range of pH, though these biopolymers had the same kind of net charge, which was evidenced from electrophoretic measurement. This clearly established the role played by selective surface patch binding driven interactions. The temperature sweep measurements conducted on these coacervate samples through rheology and differential scanning calorimetry (DSC) studies yielded two characteristic melting temperatures located at approximately 68 +/- 3 degrees C and 82 +/- 3 degrees C. In the flow mode, the shear viscosity (eta) of the coacervate samples was found to scale with (power-law model) applied shear rate (gamma*) as eta(gamma*) approximately (gamma*)(-k); this yielded k = 0.76 +/- 0.2 (1 s(-1) < gamma* < 100 s(-1)), indicating non-Newtonian behavior. The static structure factor (I(q)) deduced from small angle neutron scattering (SANS) data in the low q (q is the scattering wavevector) (0.018 A(-1) < q < 0.072 A(-1)) region was fitted to the Debye-Bueche regime, I(q) approximately 1/(1 + zeta(2)q(2))2 that yielded a size of zeta approximately 215 +/- 20 A (for r = 1:10) and zeta approximately 260 +/- 20 A (for r = 1:5) samples, implying change in the size of inhomogeneities present with mixing ratio. In the intermediate q region, called the Ornstein-Zernike regime, I(q) approximately 1/(1 + xi(2)q(2)) gave a correlation length of xi approximately 10.0 +/- 2.0 A independent of the mixing ratio. The results taken together imply the existence of a weakly interconnected and heterogeneous network structure inside the coacervate phase separated by domains of polymer-poor regions.
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Affiliation(s)
- Amar Nath Gupta
- Polymer and Biophysics Lab, School of Physical Sciences, Jawaharlal Nehru University, New Delhi-110 067, India
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Singh SS, Aswal VK, Bohidar HB. Structural studies of agar–gelatin complex coacervates by small angle neutron scattering, rheology and differential scanning calorimetry. Int J Biol Macromol 2007; 41:301-7. [PMID: 17481725 DOI: 10.1016/j.ijbiomac.2007.03.009] [Citation(s) in RCA: 61] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/01/2007] [Revised: 03/10/2007] [Accepted: 03/23/2007] [Indexed: 11/20/2022]
Abstract
Agar-gelatin complex coacervates are studied by small angle neutron scattering (SANS), rheology (in both flow and temperature scan modes) and differential scanning calorimetry (DSC) in order to probe the microscopic structure of this dense protein-polysaccharide-rich phase. DSC and isochronal temperature sweep (rheology) experiments yielded a characteristic temperature at approximately 35+/-2 degrees C. Rheology data revealed a second characteristic temperature at approximately 75+/-5 degrees C which was absent in DSC thermograms. In the flow mode, shear viscosity (eta) was found to scale with (Carreau model) applied shear rate (gamma ) as: eta(gamma ) approximately (gamma )(-k) with k=1.2+/-0.2 indicating non-Newtonian and shear-thinning features independent of ionic strength. The static structure factor S(q) deduced from SANS data in the low wave vector (0.018 A(-1)<q<0.072 A(-1)) region was fitted to Debye-Bueche function, S(q) approximately 1/(1+zeta(2)q(2))(2) that yielded a size zeta approximately 220+/-20 A identified with the size of the inhomogeneities present. In the high-q region, called the Ornstein-Zernike regime, S(q) approximately 1/(1+xi(2)q(2)) gave correlation length xi approximately 12+/-2A. The results taken together imply the existence of a weakly interconnected and heterogeneous network structure inside the coacervate phase. Structural features of this material are compared with those of agar and gelatin gel, and gelatin coacervate.
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Affiliation(s)
- S Santinath Singh
- Polymer and Biophysics Laboratory, School of Physical Sciences, Jawaharlal Nehru University, New Delhi 110016, India
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Królicka A, Kartanowicz R, Wosiński SA, Szpitter A, Kamiński M, Łojkowska E. Induction of secondary metabolite production in transformed callus of Ammi majus L. grown after electromagnetic treatment of the culture medium. Enzyme Microb Technol 2006. [DOI: 10.1016/j.enzmictec.2006.03.042] [Citation(s) in RCA: 16] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2022]
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56
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Henshaw J, Horne-Bitschy A, van Bueren AL, Money VA, Bolam DN, Czjzek M, Ekborg NA, Weiner RM, Hutcheson SW, Davies GJ, Boraston AB, Gilbert HJ. Family 6 carbohydrate binding modules in beta-agarases display exquisite selectivity for the non-reducing termini of agarose chains. J Biol Chem 2006; 281:17099-17107. [PMID: 16601125 DOI: 10.1074/jbc.m600702200] [Citation(s) in RCA: 68] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
Carbohydrate recognition is central to the biological and industrial exploitation of plant structural polysaccharides. These insoluble polymers are recalcitrant to microbial degradation, and enzymes that catalyze this process generally contain non-catalytic carbohydrate binding modules (CBMs) that potentiate activity by increasing substrate binding. Agarose, a repeat of the disaccharide 3,6-anhydro-alpha-L-galactose-(1,3)-beta-D-galactopyranose-(1,4), is the dominant matrix polysaccharide in marine algae, yet the role of CBMs in the hydrolysis of this important polymer has not previously been explored. Here we show that family 6 CBMs, present in two different beta-agarases, bind specifically to the non-reducing end of agarose chains, recognizing only the first repeat of the disaccharide. The crystal structure of one of these modules Aga16B-CBM6-2, in complex with neoagarohexaose, reveals the mechanism by which the protein displays exquisite specificity, targeting the equatorial O4 and the axial O3 of the anhydro-L-galactose. Targeting of the CBM6 to the non-reducing end of agarose chains may direct the appended catalytic modules to areas of the plant cell wall attacked by beta-agarases where the matrix polysaccharide is likely to be more amenable to further enzymic hydrolysis.
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Affiliation(s)
- Joanna Henshaw
- Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Ami Horne-Bitschy
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Alicia Lammerts van Bueren
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Victoria A Money
- Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, United Kingdom
| | - David N Bolam
- Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom
| | - Mirjam Czjzek
- Station Biologique de Roscoff, Vegetaux Marins et Biomolecules, UMR7139-CNRS-UPMC, Place George Teissier, B. P. 74, 29682 Roscoff, France
| | - Nathan A Ekborg
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Ronald M Weiner
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Steven W Hutcheson
- Department of Cell Biology and Molecular Genetics, University of Maryland, College Park, Maryland 20742
| | - Gideon J Davies
- Structural Biology Laboratory, Department of Chemistry, University of York, Heslington, York YO10 5YW, United Kingdom
| | - Alisdair B Boraston
- Department of Biochemistry and Microbiology, University of Victoria, Victoria, British Columbia V8W 3P6, Canada
| | - Harry J Gilbert
- Institute for Cell and Molecular Biosciences, University of Newcastle upon Tyne, Framlington Place, Newcastle upon Tyne NE2 4HH, United Kingdom.
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Jiu J, Kurumada KI, Pei L, Tanigaki M. Syntheses of ordered mesoporous silica by new hybrid template. Colloids Surf B Biointerfaces 2004; 38:121-5. [PMID: 15542312 DOI: 10.1016/j.colsurfb.2004.04.010] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2003] [Accepted: 04/26/2004] [Indexed: 11/16/2022]
Abstract
Ordered mesoporous silica with macroscopic shape has been prepared with a hybrid template of gel and poly(ethylene oxide)106-poly(propylene oxide)70-poly(ethylene oxide)106 (pluronic F127) surfactant, where both water-soluble agar gel and pluronic F127 significantly affect the mesoporous structure and morphology of silica. The thermal analysis revealed the noticeable interaction between agar and F127, which contributes to the formation of homogenous hybrid template. In the hybrid template, agar gel contributed to the maintenance of morphology structure, while F127 was responsible for the formation of ordered porous structure in silica solids.
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Affiliation(s)
- Jinting Jiu
- Department of Chemical Engineering, Faculty of Engineering, Kyoto University, Yoshida-Honmachi, Sakyo-Ku, Kyoto 606-8501, Japan.
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