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Nsengiyumva EM, Heitz MP, Alexandridis P. Carboxymethyl hydroxypropyl guar gum physicochemical properties in dilute aqueous media. Int J Biol Macromol 2024; 262:129775. [PMID: 38423913 DOI: 10.1016/j.ijbiomac.2024.129775] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/06/2023] [Revised: 01/15/2024] [Accepted: 01/24/2024] [Indexed: 03/02/2024]
Abstract
We investigate carboxymethyl hydroxypropyl guar gum (CMHPG) solution properties in water and NaCl, KCl, and CaCl2 aqueous solutions. The Huggins, Kraemer, and Rao models were applied by fitting specific and relative viscosity of CMHPG/water and CMHPG/salt/water to determine the intrinsic viscosity [η]. The Rao models yielded better results (R2 = 0.779-0.999) than Huggins and Kraemer equations. [η] decreased up to 84% in salt solution over the range 0.9-100 mM compared to water. Salt effects screened the CMHPG charged side groups chains leading to a compacted structure. In 0.9 mM NaCl(aq), the hydrodynamic coil radius (Rcoil) was 28% smaller and 45% smaller in 100 mM NaCl solution relative to water. Similar decreases were seen in KCl and CaCl2 solutions. KCl and CaCl2 were more effective than NaCl. CMHPG is salt-tolerant and shows comparatively less viscosity change than native guar gum, with modest reduced viscosity increases with CMHPG dilution at all salt concentrations. The electrostatic interactions were effective up to 100 mM salt. The activation energy of viscous flow for CMHPG solutions was computed and compared to measured xanthan gum and several literature values. These data show that the barrier to CMHPG flow is higher than for xanthan gum.
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Affiliation(s)
- Emmanuel M Nsengiyumva
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260-4200, USA; Department of Chemistry and Biochemistry, The State University of New York (SUNY) Brockport, Brockport, NY 14420, USA
| | - Mark P Heitz
- Department of Chemistry and Biochemistry, The State University of New York (SUNY) Brockport, Brockport, NY 14420, USA.
| | - Paschalis Alexandridis
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260-4200, USA.
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Nsengiyumva EM, Heitz MP, Alexandridis P. Salt and Temperature Effects on Xanthan Gum Polysaccharide in Aqueous Solutions. Int J Mol Sci 2023; 25:490. [PMID: 38203659 PMCID: PMC10778890 DOI: 10.3390/ijms25010490] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2023] [Revised: 12/20/2023] [Accepted: 12/28/2023] [Indexed: 01/12/2024] Open
Abstract
Xanthan gum (XG) is a carbohydrate polymer with anionic properties that is widely used as a rheology modifier in various applications, including foods and petroleum extraction. The aim was to investigate the effect of Na+, K+, and Ca2+ on the physicochemical properties of XG in an aqueous solution as a function of temperature. Huggins, Kraemer, and Rao models were applied to determine intrinsic viscosity, [η], by fitting the relative viscosity (ηrel) or specific viscosity (ηsp) of XG/water and XG/salt/water solutions. With increasing temperature in water, Rao 1 gave [η] the closest to the Huggins and Kraemer values. In water, [η] was more sensitive to temperature increase (~30% increase in [η], 20-50 °C) compared to salt solutions (~15-25% increase). At a constant temperature, salt counterions screened the XG side-chain-charged groups and decreased [η] by up to 60% over 0.05-100 mM salt. Overall, Ca2+ was much more effective than the monovalent cations in screening charge. As the salt valency and concentration increased, the XG coil radius decreased, making evident the effect of shielding the intramolecular and intermolecular XG anionic charge. The reduction in repulsive forces caused XG structural contraction. Further, higher temperatures led to chain expansion that facilitated increased intermolecular interactions, which worked against the salt effect.
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Affiliation(s)
- Emmanuel M. Nsengiyumva
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260, USA;
- Department of Chemistry and Biochemistry, The State University of New York (SUNY) Brockport, Brockport, NY 14420, USA
| | - Mark P. Heitz
- Department of Chemistry and Biochemistry, The State University of New York (SUNY) Brockport, Brockport, NY 14420, USA
| | - Paschalis Alexandridis
- Department of Chemical and Biological Engineering, University at Buffalo, The State University of New York (SUNY), Buffalo, NY 14260, USA;
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LaRocca MM, Baker GA, Heitz MP. Assessing rotation and solvation dynamics in ethaline deep eutectic solvent and its solutions with methanol. J Chem Phys 2021; 155:034505. [PMID: 34293899 DOI: 10.1063/5.0056653] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/21/2023] Open
Abstract
Steady-state and time-resolved fluorescence were used to investigate the solvation of coumarin 153 (C153) and coumarin 343 (C343) in methanol + ethaline binary solutions, a deep eutectic solvent composed of a 1:2 molar ratio choline chloride + ethylene glycol. In addition, time-resolved anisotropy decays were used to determine the solute's rotational reorientation time as a function of viscosity. Measurements were made in solutions covering the entire range of mole fraction. Viscosity measurements were used to characterize the bulk solvent properties, and as expected, addition of methanol resulted in an decreased viscosity, showing an exponential decrease with mole fraction, up to ∼50-fold at xMeOH = 1.0. Probe rotational reorientation times were found to be biexponential at xMeOH < 0.3 for C153 and xMeOH < 0.5 for C343 and monoexponential at richer methanol content. In proportion to viscosity, C153 and C343 average rotation times decreased ∼30-fold from xMeOH = 0 to 0.9 and showed a power law dependence of ∼η0.85. Rotation times approached the stick boundary limit on dilution with methanol. Time-resolved Stokes shifts quantified the solvation dynamics and were nearly single exponential for C153 but were clearly biexponential for C343. Solvation times also tracked with viscosity according to a power law dependence, with exponents of 0.3 and 0.4 for C153 and C343, respectively. The dilution effect of methanol was not linear in proportion to the viscosity change and alone cannot account for the change in solvation. Dilution also showed a different correlation to solvation than did temperature variations to govern the viscosity change.
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Affiliation(s)
- Mary M LaRocca
- Department of Chemistry and Biochemistry, SUNY Brockport, Brockport, New York 14420, USA
| | - Gary A Baker
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Mark P Heitz
- Department of Chemistry and Biochemistry, SUNY Brockport, Brockport, New York 14420, USA
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Bhushan V, Heitz MP, Baker GA, Pandey S. Ionic Liquid-Controlled Shape Transformation of Spherical to Nonspherical Polymersomes via Hierarchical Self-Assembly of a Diblock Copolymer. Langmuir 2021; 37:5081-5088. [PMID: 33845575 DOI: 10.1021/acs.langmuir.1c00821] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/12/2023]
Abstract
Here, we report the self-assembly of poly(ethylene glycol) methyl ether-block-poly(ε-caprolactone) (PEG-b-PCL) copolymer in three ionic liquids (ILs) possessing different cations with common bis(trifluoromethylsulfonyl)imide anion. The observed polymeric nanostructures in ILs were directly visualized by room temperature conventional transmission and field emission scanning electron microscopy and were further examined for their size and shape by dynamic light scattering technique. The results show that through changes in the concentration of PEG-b-PCL and/or changing the solvent by using a different IL, we can effectively induce shape transformation of self-assembled PEG-b-PCL nanostructures in order to generate nonspherical polymersomes, such as worm-like aggregates, stomatocytes, nanotubes, large hexagonal and tubular-shaped polymersomes. These findings provide a promising platform for the design of biodegradable soft dynamic systems in the micro-/nano-motor field for cancer-targeted delivery, diagnosis and imaging-guided therapy, and controlled release of therapeutic drugs for treatment of many diseases. Non-spherical polymersome-based vaccines may be taken up more efficiently, especially against viruses for pulmonary drug delivery than the spherical polymersomes-based.
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Affiliation(s)
- Vidiksha Bhushan
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
| | - Mark P Heitz
- Department of Chemistry and Biochemistry, State University of New York at Brockport, Brockport, New York, New York 14420, United States
| | - Gary A Baker
- Department of Chemistry, University of Missouri, Columbia, Missouri 65211, United States
| | - Siddharth Pandey
- Department of Chemistry, Indian Institute of Technology Delhi, Hauz Khas, New Delhi 110016, India
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Smith CJ, Gehrke S, Hollóczki O, Wagle DV, Heitz MP, Baker GA. NMR relaxometric probing of ionic liquid dynamics and diffusion under mesoscopic confinement within bacterial cellulose ionogels. J Chem Phys 2018; 148:193845. [PMID: 30307178 DOI: 10.1063/1.5016337] [Citation(s) in RCA: 8] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Affiliation(s)
- Chip J. Smith
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Sascha Gehrke
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, Bonn 53115, Germany
- Max Planck Institute for Chemical Energy Conversion, Stiftstr. 34-36, Muelheim an der Ruhr 45470, Germany
| | - Oldamur Hollóczki
- Mulliken Center for Theoretical Chemistry, University of Bonn, Beringstr. 4+6, Bonn 53115, Germany
| | - Durgesh V. Wagle
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
| | - Mark P. Heitz
- Department of Chemistry and Biochemistry, The College at Brockport SUNY, Brockport, New York 14420, USA
| | - Gary A. Baker
- Department of Chemistry, University of Missouri-Columbia, Columbia, Missouri 65211, USA
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P Heitz M, W Rupp J, W Horn K. Biocatalytic Activity of Mushroom Tyrosinase in Ionic Liquids: Specific Ion Effects and the Hofmeister Series. ACTA ACUST UNITED AC 2018. [DOI: 10.21767/2573-4466.100012] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [What about the content of this article? (0)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2022]
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Heitz MP, Rupp JW. Determining mushroom tyrosinase inhibition by imidazolium ionic liquids: A spectroscopic and molecular docking study. Int J Biol Macromol 2017; 107:1971-1981. [PMID: 29032215 DOI: 10.1016/j.ijbiomac.2017.10.066] [Citation(s) in RCA: 24] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2017] [Revised: 09/30/2017] [Accepted: 10/11/2017] [Indexed: 01/12/2023]
Abstract
The inhibition effects of imidazolium ionic liquids (ILs) on the enzyme kinetics of mushroom tyrosinase is reported. A simple UV-VIS spectrophotometric assay was used to measure the reaction kinetics of the reaction between mushroom tyrosinase and L-dopa. Seven different imidazolium ILs, comprised of 1-alkyl-3-methylimidazolium ([Imn1+], n=2, 4, 6) cations paired with several anions that included Cl-, [NO3-], methanesulfonate ([MeSO3-]), trifluoromethanesulfonate (or triflate, [TFMS-]), and bis(trifluoromethylsulfonyl)imide ([Tf2N-]). Lineweaver-Burk plots were generated from the recovered kcat and Km parameters using four to six substrate concentrations per measurement. The results show that mushroom tyrosinase activity was consistently inhibited by all of the ILs and that the type of inhibition was non-competitive in nearly all cases. Only the data for [Im21+][Tf2N-] suggested that the inhibition mechanism was competitive with the substrate. Molecular docking simulations were performed using AutoDock4.2 and AutoDock Vina and revealed that all cations docked in the L-dopa active site. Anions showed varied results that included locations both within and outside of the active site.
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Affiliation(s)
- Mark P Heitz
- Department of Chemistry and Biochemistry, The College at Brockport, SUNY, 228, Smith Hall 350 New Campus Drive, Brockport, NY, 14420, United States.
| | - Jason W Rupp
- Department of Chemistry and Biochemistry, The College at Brockport, SUNY, 228, Smith Hall 350 New Campus Drive, Brockport, NY, 14420, United States
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Barra KM, Sabatini RP, McAtee ZP, Heitz MP. Solvation and Rotation Dynamics in the Trihexyl(tetradecyl)phosphonium Chloride Ionic Liquid/Methanol Cosolvent System. J Phys Chem B 2014; 118:12979-92. [DOI: 10.1021/jp5092784] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Kathleen M. Barra
- Department
of Chemistry, The College at Brockport, State University of New York, Brockport, New York 14420, United States
| | - Randy P. Sabatini
- Department
of Chemistry, The College at Brockport, State University of New York, Brockport, New York 14420, United States
| | - Zachery P. McAtee
- Department
of Chemistry, The College at Brockport, State University of New York, Brockport, New York 14420, United States
| | - Mark P. Heitz
- Department
of Chemistry, The College at Brockport, State University of New York, Brockport, New York 14420, United States
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Affiliation(s)
- Markus M. Hoffmann
- a Department of Chemistry , State University of New York, College at Brockport , 350 New Campus Drive, Brockport , New York , 14420 , USA
| | - Mark P. Heitz
- a Department of Chemistry , State University of New York, College at Brockport , 350 New Campus Drive, Brockport , New York , 14420 , USA
| | - Jason B. Carr
- a Department of Chemistry , State University of New York, College at Brockport , 350 New Campus Drive, Brockport , New York , 14420 , USA
| | - Jason D. Tubbs
- a Department of Chemistry , State University of New York, College at Brockport , 350 New Campus Drive, Brockport , New York , 14420 , USA
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Walter L, Nogueira V, Leverve X, Heitz MP, Bernardi P, Fontaine E. Three classes of ubiquinone analogs regulate the mitochondrial permeability transition pore through a common site. J Biol Chem 2000; 275:29521-7. [PMID: 10889201 DOI: 10.1074/jbc.m004128200] [Citation(s) in RCA: 115] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022] Open
Abstract
To identify the structural features required for regulation of the mitochondrial permeability transition pore (PTP) by ubiquinone analogs (Fontaine, E., Ichas, F., and Bernardi, P. (1998) J. Biol. Chem. 40, 25734-25740), we have carried out an analysis with quinone structural variants. We show that three functional classes can be defined: (i) PTP inhibitors (ubiquinone 0, decylubiquinone, ubiquinone 10, 2,3-dimethyl-6-decyl-1,4-benzoquinone, and 2,3,5-trimethyl-6-geranyl-1,4-benzoquinone); (ii) PTP inducers (2,3-dimethoxy-5-methyl-6-(10-hydroxydecyl)-1,4-benzoquinone and 2,5-dihydroxy-6-undecyl-1,4-benzoquinone); and (iii) PTP-inactive quinones that counteract the effects of both inhibitors and inducers (ubiquinone 5 and 2,3,5-trimethyl-6-(3-hydroxyisoamyl)-1,4-benzoquinone) . The structure-function correlation indicates that minor modifications in the isoprenoid side chain can turn an inhibitor into an activator, and that the methoxy groups are not essential for the effects of quinones on the PTP. Since the ubiquinone analogs used in this study have a similar midpoint potential and decrease mitochondrial production of reactive oxygen species to the same extent, these results support the hypothesis that quinones modulate the PTP through a common binding site rather than through oxidation-reduction reactions. Occupancy of this site can modulate the PTP open-closed transitions, possibly through secondary changes of the PTP Ca(2+) binding affinity.
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Affiliation(s)
- L Walter
- Laboratoire de Bioénergétique Fondamentale et Appliquée, Université Joseph Fourier, F-38041 Grenoble cedex 09, France
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Fischer G, Mutel V, Trube G, Malherbe P, Kew JN, Mohacsi E, Heitz MP, Kemp JA. Ro 25-6981, a highly potent and selective blocker of N-methyl-D-aspartate receptors containing the NR2B subunit. Characterization in vitro. J Pharmacol Exp Ther 1997; 283:1285-92. [PMID: 9400004] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023] Open
Abstract
The interaction of Ro 25-6981 with N-methyl-D-aspartate (NMDA) receptors was characterized by a variety of different tests in vitro. Ro 25-6981 inhibited 3H-MK-801 binding to rat forebrain membranes in a biphasic manner with IC50 values of 0.003 microM and 149 microM for high- (about 60%) and low-affinity sites, respectively. NMDA receptor subtypes expressed in Xenopus oocytes were blocked with IC50 values of 0.009 microM and 52 microM for the subunit combinations NR1C & NR2B and NR1C & NR2A, respectively, which indicated a >5000-fold selectivity. Like ifenprodil, Ro 25-6981 blocked NMDA receptor subtypes in an activity-dependent manner. Ro 25-6981 protected cultured cortical neurons against glutamate toxicity (16 h exposure to 300 microM glutamate) and combined oxygen and glucose deprivation (60 min followed by 20 h recovery) with IC50 values of 0.4 microM and 0.04 microM, respectively. Ro 25-6981 was more potent than ifenprodil in all of these tests. It showed no protection against kainate toxicity (exposure to 500 microM for 20 h) and only weak activity in blocking Na+ and Ca++ channels, activated by exposure of cortical neurons to veratridine (10 microM) and potassium (50 mM), respectively. These findings demonstrate that Ro 25-6981 is a highly selective, activity-dependent blocker of NMDA receptors that contain the NR2B subunit.
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Affiliation(s)
- G Fischer
- Pharma Division, Preclinical CNS Research, F. Hoffmann-La Roche Ltd., CH-4070 Basel, Switzerland
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Schaffhauser H, de Barry J, Muller H, Heitz MP, Gombos G, Mutel V. Involvement of a cyclic-AMP pathway in group I metabotropic glutamate receptor responses in neonatal rat cortex. Eur J Pharmacol 1997; 334:289-97. [PMID: 9369360 DOI: 10.1016/s0014-2999(97)01192-8] [Citation(s) in RCA: 12] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/05/2023]
Abstract
3,5-Dihydroxyphenylglycine (DHPG), (S)-3-hydroxyphenylglycine and (S)-4-carboxy-3-hydroxyphenylglycine (S-4C3HPG) stimulated phosphoinositide hydrolysis in neonatal rat cortical slices, but with lower maximal effect, in comparison with 2S,1'S,2'S-2-(2'-carboxycyclopropyl)glycine (L-CCG I) or (1S,3R)-1-aminocyclo-pentane-1,3-dicarboxylic acid (1S,3R-ACPD). DHPG, 1S,3R-ACPD, and S-4C3HPG also evoked a rapidly desensitizing increase in [Ca2+]i in cortical layers of neonatal brain slices. (R,S)-alpha-methyl-4-tetrazolyl-phenylglycine (MTPG), and (R,S)-alpha-methyl-4-phosphono-phenylglycine (MPPG) inhibited the increase of phosphoinositide hydrolysis elicited by 1S,3R-ACPD but not that by R,S-DHPG. In contrast, the selective group II receptor agonist (1S,2S,5R,6S)-2-amino-bicyclo-[3.1.0]-hexane-2,6-dicarboxylate (LY 354740) potentiated the response of R,S-DHPG. Finally, 8-(4-chlorophenylthio)-cAMP, a membrane permeant analogue of cAMP, reversed the stimulatory effect of 1S,3R-ACPD and S-4C3HPG on phosphoinositide hydrolysis and [Ca2+]i mobilization, without affecting the response induced by R,S-DHPG. These data suggest that, in neonatal rat cortex, the activation of group II metabotropic glutamate receptors potentiates the phosphoinositide hydrolysis and [Ca2+]i responses mediated by group I metabotropic glutamate receptors.
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Affiliation(s)
- H Schaffhauser
- Pharma Division Preclinical CNS Research, F. Hoffmann-La Roche Ltd., Basel, Switzerland
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Heitz MP, Carlier C, deGrazia J, Harrison KL, Johnston KP, Randolph TW, Bright FV. Water Core within Perfluoropolyether-Based Microemulsions Formed in Supercritical Carbon Dioxide. J Phys Chem B 1997. [DOI: 10.1021/jp9622243] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Affiliation(s)
- Mark P. Heitz
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Claude Carlier
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Janet deGrazia
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Kristi L. Harrison
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Keith P. Johnston
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Theodore W. Randolph
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
| | - Frank V. Bright
- Department of Chemistry, Natural Sciences Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000, Department of Chemical Engineering, University of Colorado at Boulder, Boulder, Colorado 80309-0424, and Department of Chemical Engineering, University of Texas at Austin, Austin, Texas 78712
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Heitz MP, Bright FV. Probing the Scale of Local Density Augmentation in Supercritical Fluids: A Picosecond Rotational Reorientation Study. ACTA ACUST UNITED AC 1996. [DOI: 10.1021/jp953589a] [Citation(s) in RCA: 60] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Mark P. Heitz
- Department of Chemistry, Natural Sciences and Mathematics Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000
| | - Frank V. Bright
- Department of Chemistry, Natural Sciences and Mathematics Complex, State University of New York at Buffalo, Buffalo, New York 14260-3000
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Cesura AM, Alberati-Giani D, Buchli R, Broger C, Köhler C, Vilbois F, Lahm HW, Heitz MP, Malherbe P. Molecular characterisation of kynurenine pathway enzymes. 3-Hydroxyanthranilic-acid dioxygenase and kynurenine aminotransferase. Adv Exp Med Biol 1996; 398:477-83. [PMID: 8906308 DOI: 10.1007/978-1-4613-0381-7_74] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 02/03/2023]
Affiliation(s)
- A M Cesura
- Pharma Division, Preclinical Research, Nervous System Diseases, F. Hoffmann-La Roche Ltd. Basel, Switzerland
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Abstract
We investigate the effects of hydration on acrylodan-labeled bovine and human serum albumin (BSA-Ac and HSA-Ac) in aerosol-OT (AOT) reverse micelles solubilized in n-heptane. Time-resolved fluorescence intensity decay experiments reveal a dipolar relaxation process surrounding the acrylodan cybotactic region. This process is best described by a two-term rate law wherein the average relaxation increases with increased hydration. However, the actual rate constants describing the relaxation process either remain unchanged or actually decrease with increased hydration. The results illustrate that the fractional contribution associated with the individual relaxation pathways causes the observed changes in relaxation dynamics. The recovered rotational reorientation dynamics of the acrylodan residue are also affected by the extent of protein hydration. As hydration is increased, the semiangle through which the acrylodan residue precesses increases by 10 degrees for both protein systems. Interestingly, the recovered semiangles for the native proteins equal those recovered at lower hydration when the proteins are sequestered within the AOT reverse micelle. These results demonstrate the importance of hydration on protein behavior in environments where water is limited (e.g., biosensor interfaces and sol--gel-derived biocomposites).
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Affiliation(s)
- J S Lundgren
- Department of Chemistry, State University of New York at Buffalo 14260-3000, USA
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