1
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Choudhury A, Khanppnavar B, Datta S. Crystallographic and biophysical analyses of Pseudomonas aeruginosa ketopantoate reductase: Implications of ligand induced conformational changes in cofactor recognition. Biochimie 2021; 193:103-114. [PMID: 34757166 DOI: 10.1016/j.biochi.2021.10.015] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/14/2021] [Revised: 10/15/2021] [Accepted: 10/28/2021] [Indexed: 11/26/2022]
Abstract
Ketopantoate reductases (KPRs) catalyse NADPH-dependent reduction of ketopantoate to pantoate, the rate-limiting step of pantothenate biosynthetic pathway. In our recent study, we showed KPRs are under dynamic evolutionary selection and highlighted the possible role of ordered substrate binding kinetics for cofactor selection. To further delineate this at molecular level, here, we perform X-ray crystallographic and biophysical analyses of KPR in presence of non-canonical cofactor NAD+. In our structure, NAD+ was found to be highly dynamic in catalytic pocket of KPR, which could attain stable conformation only in presence of ketopantoate. Further, isothermal calorimetric (ITC) titrations showed that affinity of KPR for ketopantoate is higher in presence of NADP+ than in presence of NAD+ and lowest in absence of redox cofactors. In sum, our results clearly depict two modes of redox cofactor selections in KPRs, firstly by specific salt bridge interactions with unique phosphate moiety of NADP+ and secondly via ordered sequential heterotrophic cooperative binding of substrate ketopantoate.
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Affiliation(s)
- Arkaprabha Choudhury
- Department of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology (CSIR-IICB), Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Basavraj Khanppnavar
- Department of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology (CSIR-IICB), Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), India
| | - Saumen Datta
- Department of Structural Biology and Bioinformatics, CSIR-Indian Institute of Chemical Biology (CSIR-IICB), Kolkata, India; Academy of Scientific and Innovative Research (AcSIR), India.
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2
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Yu F, Tonnis K, Xu L, Jaworska J, Kasting GB. Modeling the Percutaneous Absorption of Solvent-deposited Solids Over a Wide Dose Range. J Pharm Sci 2021; 111:769-779. [PMID: 34627876 DOI: 10.1016/j.xphs.2021.10.001] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/09/2021] [Revised: 10/02/2021] [Accepted: 10/03/2021] [Indexed: 10/20/2022]
Abstract
The transient absorption of two skin care agents, niacinamide (nicotinamide, NA) and methyl nicotinate (MN), solvent-deposited on ex vivo human skin mounted in Franz diffusion cells has been analyzed according to a new variation on a recently published mechanistic skin permeability model (Yu et al. 2020. J Pharm Sci 110:2149-56). The model follows the absorption and evaporation of two components, solute and solvent, and it includes both a follicular transport component and a dissolution rate limitation for high melting, hydrophilic solids deposited on the skin. Explicit algorithms for improving the simulation of transient diffusion of solvent-deposited solids are introduced. The simulations can account for the ex vivo skin permeation time course of both NA and MN over a dose range exceeding 4.5 orders of magnitude. The model allows one to describe on a mechanistic basis why the percutaneous absorption rate of NA is approximately 60-fold lower than that of its lower melting, more lipophilic analog, MN. It furthermore suggests that MN perturbs stratum corneum barrier lipids and increases their permeability while NA does not, presenting a challenge to molecular modelers engaged in simulating biological lipid barriers.
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Affiliation(s)
- Fang Yu
- College of Engineering and Applied Science, The University of Cincinnati, Cincinnati, Ohio, USA
| | - Kevin Tonnis
- College of Engineering and Applied Science, The University of Cincinnati, Cincinnati, Ohio, USA
| | - Lijing Xu
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, Ohio, USA
| | - Joanna Jaworska
- The Procter & Gamble Company, Data and Modeling Sciences, Brussels Innovation Center, Belgium
| | - Gerald B Kasting
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, Ohio, USA.
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3
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Kasting GB, Miller MA, Xu L, Yu F, Jaworska J. In Vitro Human Skin Absorption of Solvent-deposited Solids: Niacinamide and Methyl Nicotinate. J Pharm Sci 2021; 111:727-733. [PMID: 34600943 DOI: 10.1016/j.xphs.2021.09.040] [Citation(s) in RCA: 6] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/15/2021] [Revised: 09/26/2021] [Accepted: 09/26/2021] [Indexed: 11/17/2022]
Abstract
A quantitative understanding of the dose dependence of topical delivery is important to cosmetic and dermatological product development and to risk assessment for hazardous chemicals contacting the skin. Despite considerable research, predictive capability in this area remains limited. To this end we conducted an experimental skin absorption study of two closely related skin care agents, niacinamide (nicotinamide, NA) and methyl nicotinate (MN), and analyzed the results quantitatively using a transient diffusion model described separately (Yu et al. submitted for publication). Radiolabeled test compounds were solvent-deposited onto ex vivo human skin mounted in Franz diffusion cells over a dose range exceeding 4.5 orders of magnitude, and permeation was measured over a 1-4 day period. At low doses, the permeation rate of NA was approximately 60-fold lower than that of its lower melting, more lipophilic analog, MN; at high doses an even greater difference was observed. The difference can be qualitatively explained based on higher lipid solubility and lower crystallinity of MN relative to NA. Dissolution-limited mass transfer through a lipid layer at the SC surface is suggested. Relevance of the results to practical skin care formulations was confirmed by a parallel study of NA in an o/w emulsion.
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Affiliation(s)
- Gerald B Kasting
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH, USA.
| | - Matthew A Miller
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH, USA
| | - Lijing Xu
- The James L. Winkle College of Pharmacy, The University of Cincinnati, Cincinnati, OH, USA
| | - Fang Yu
- College of Engineering and Applied Science, The University of Cincinnati, Cincinnati, OH, USA
| | - Joanna Jaworska
- The Procter & Gamble Company, Data and Modeling Sciences, Brussels Innovation Center, Belgium
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4
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Omori M, Watanabe T, Uekusa T, Oki J, Inoue D, Sugano K. Effects of Coformer and Polymer on Particle Surface Solution-Mediated Phase Transformation of Cocrystals in Aqueous Media. Mol Pharm 2020; 17:3825-3836. [PMID: 32870691 DOI: 10.1021/acs.molpharmaceut.0c00587] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/29/2023]
Abstract
The purpose of the present study was to investigate the effect of the coformer difference on particle surface solution-mediated phase transformation (PS-SMPT) during cocrystal particle dissolution in aqueous media in the absence and presence of polymers. SMPT can occur either in the bulk phase or at the particle surface because drug molecules can be supersaturated at the dissolving cocrystal surface, as well as in the bulk phase. Previously, bulk phase SMPT has been primarily investigated in formulation development. However, little is known about the effects of coformers and polymers on PS-SMPT of cocrystals. In this study, six carbamazepine (CBZ) cocrystals were used as model cocrystals (malonic acid (MAL), succinic acid (SUC), glutaric acid (GLA), adipic acid (ADP), saccharin (SAC), and nicotinamide (NCT); nonsink dissolution tests were performed with or without a precipitation inhibitor (hydroxypropyl methylcellulose (HPMC)) at pH 6.5. The residual particles were analyzed by powder X-ray diffraction, differential scanning calorimetry, polarized light microscopy (PLM), and scanning electron microscopy. Real-time PLM was used to directly observe rapid PS-SMPT. In the absence of HPMC, supersaturation was not observed in the bulk phase for all cocrystals. All cocrystals rapidly transformed to CBZ dihydrate aggregates via PS-SMPT (mostly within 1 min). In contrast, in the presence of 0.1% HPMC, supersaturation was observed for CBZ-SUC, CBZ-ADP, CBZ-SAC, and CBZ-NCT but not for CBZ-MAL and CBZ-GLA. The cocrystals with lower solubility coformers tended to induce higher supersaturation in the bulk phase. The PS-SMPT of CBZ-SUC, CBZ-ADP, and CBZ-SAC was slowed down by HPMC. By suppressing PS-SMPT, the cocrystals exhibited its supersaturation potential, depending on the properties of each coformer. To take advantage of the supersaturation potential of cocrystals to improve oral drug absorption, it is important to suppress particle surface SMPT in addition to bulk phase SMPT.
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Affiliation(s)
- Maaya Omori
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Tomohiro Watanabe
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Taiga Uekusa
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Jumpei Oki
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Daisuke Inoue
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
| | - Kiyohiko Sugano
- Molecular Pharmaceutics Lab., College of Pharmaceutical Sciences, Ritsumeikan University, 1-1-1 Noji-higashi, Kusatsu, Shiga 525-8577, Japan
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5
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Zhu S. Validation of the Generalized Force Fields GAFF, CGenFF, OPLS-AA, and PRODRGFF by Testing Against Experimental Osmotic Coefficient Data for Small Drug-Like Molecules. J Chem Inf Model 2019; 59:4239-4247. [DOI: 10.1021/acs.jcim.9b00552] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023]
Affiliation(s)
- Shun Zhu
- Department of Cellular and Genetic Medicine, School of Basic Medical Sciences, Fudan University, Shanghai 200032, P.R. China
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7
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Self-Assembly of α-Cyclodextrin and β-Cyclodextrin: Identification and Development of Analytical Techniques. J Pharm Sci 2018; 107:2208-2215. [DOI: 10.1016/j.xphs.2018.03.028] [Citation(s) in RCA: 12] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2018] [Revised: 03/23/2018] [Accepted: 03/30/2018] [Indexed: 12/17/2022]
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8
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Shen J, Terskikh V, Wang X, Hung I, Gan Z, Wu G. A Quadrupole-Central-Transition 17O NMR Study of Nicotinamide: Experimental Evidence of Cross-Correlation between Second-Order Quadrupolar Interaction and Magnetic Shielding Anisotropy. J Phys Chem B 2018; 122:4813-4820. [PMID: 29683675 DOI: 10.1021/acs.jpcb.8b02417] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We have examined the 17O quadrupole-central-transition (QCT) NMR signal from [17O]nicotinamide (vitamin B3) dissolved in glycerol. Measurements were performed at five magnetic fields ranging from 9.4 to 35.2 T between 243 and 363 K. We found that, in the ultraslow motion regime, cross-correlation between the second-order quadrupole interaction and magnetic shielding anisotropy is an important contributor to the transverse relaxation process for the 17O QCT signal of [17O]nicotinamide. While such a cross-correlation effect has generally been predicted by relaxation theory, we report here the first experimental evidence for this phenomenon in solution-state NMR for quadrupolar nuclei. We have discussed the various factors that determine the ultimate resolution limit in QCT NMR spectroscopy. The present study also highlights the advantages of performing QCT NMR experiments at very high magnetic fields (e.g., 35.2 T).
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Affiliation(s)
- Jiahui Shen
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada K7L 3N6
| | - Victor Terskikh
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada K7L 3N6.,Department of Chemistry , University of Ottawa , Ottawa , Ontario , Canada K1N 6N5
| | - Xiaoling Wang
- National High Magnetic Field Laboratory , 1800 East Paul Dirac Drive , Tallahassee , Florida 32310 , United States
| | - Ivan Hung
- National High Magnetic Field Laboratory , 1800 East Paul Dirac Drive , Tallahassee , Florida 32310 , United States
| | - Zhehong Gan
- National High Magnetic Field Laboratory , 1800 East Paul Dirac Drive , Tallahassee , Florida 32310 , United States
| | - Gang Wu
- Department of Chemistry , Queen's University , 90 Bader Lane , Kingston , Ontario , Canada K7L 3N6
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9
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Miller MS, Lay WK, Li S, Hacker WC, An J, Ren J, Elcock AH. Reparametrization of Protein Force Field Nonbonded Interactions Guided by Osmotic Coefficient Measurements from Molecular Dynamics Simulations. J Chem Theory Comput 2017; 13:1812-1826. [PMID: 28296391 PMCID: PMC5543770 DOI: 10.1021/acs.jctc.6b01059] [Citation(s) in RCA: 30] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
There is a small, but growing, body of literature describing the use of osmotic coefficient measurements to validate and reparametrize simulation force fields. Here we have investigated the ability of five very commonly used force field and water model combinations to reproduce the osmotic coefficients of seven neutral amino acids and five small molecules. The force fields tested include AMBER ff99SB-ILDN, CHARMM36, GROMOS54a7, and OPLS-AA, with the first of these tested in conjunction with the TIP3P and TIP4P-Ew water models. In general, for both the amino acids and the small molecules, the tested force fields produce computed osmotic coefficients that are lower than experiment; this is indicative of excessively favorable solute-solute interactions. The sole exception to this general trend is provided by GROMOS54a7 when applied to amino acids: in this case, the computed osmotic coefficients are consistently too high. Importantly, we show that all of the force fields tested can be made to accurately reproduce the experimental osmotic coefficients of the amino acids when minor modifications-some previously reported by others and some that are new to this study-are made to the van der Waals interactions of the charged terminal groups. Special care is required, however, when simulating Proline with a number of the force fields, and a hydroxyl-group specific modification is required in order to correct Serine and Threonine when simulated with AMBER ff99SB-ILDN. Interestingly, an alternative parametrization of the van der Waals interactions in the latter force field, proposed by the Nerenberg and Head-Gordon groups, is shown to immediately produce osmotic coefficients that are in excellent agreement with experiment. Overall, this study reinforces the idea that osmotic coefficient measurements can be used to identify general shortcomings in commonly used force fields' descriptions of solute-solute interactions and further demonstrates that modifications to van der Waals parameters provide a simple route to optimizing agreement with experiment.
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Affiliation(s)
- Mark S. Miller
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | - Wesley K. Lay
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | - Shuxiang Li
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | | | - Jiadi An
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | - Jianlan Ren
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
| | - Adrian H. Elcock
- Department of Biochemistry, University of Iowa, Iowa City, IA 52242
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10
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Strategies for improving the payload of small molecular drugs in polymeric micelles. J Control Release 2017; 261:352-366. [PMID: 28163211 DOI: 10.1016/j.jconrel.2017.01.047] [Citation(s) in RCA: 73] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/22/2016] [Revised: 01/27/2017] [Accepted: 01/30/2017] [Indexed: 11/24/2022]
Abstract
In the past few years, substantial efforts have been made in the design and preparation of polymeric micelles as novel drug delivery vehicles. Typically, polymeric micelles possess a spherical core-shell structure, with a hydrophobic core and a hydrophilic shell. Consequently, poorly water-soluble drugs can be effectively solubilized within the hydrophobic core, which can significantly boost their drug loading in aqueous media. This leads to new opportunities for some bioactive compounds that have previously been abandoned due to their low aqueous solubility. Even so, the payload of small molecular drugs is still not often satisfactory due to low drug loading and premature release, which makes it difficult to meet the requirements of in vivo studies. This problem has been a major focus in recent years. Following an analysis of the published literature in this field, several strategies towards achieving polymeric micelles with high drug loading and stability are presented in this review, in order to ensure adequate drug levels reach target sites.
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11
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Matthews E, Dessent CEH. Locating the Proton in Nicotinamide Protomers via Low-Resolution UV Action Spectroscopy of Electrosprayed Solutions. J Phys Chem A 2016; 120:9209-9216. [DOI: 10.1021/acs.jpca.6b10433] [Citation(s) in RCA: 27] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/02/2023]
Affiliation(s)
- Edward Matthews
- Department of Chemistry, University of York, Heslington, York, YO10 5DD, U.K
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12
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Booth JJ, Omar M, Abbott S, Shimizu S. Hydrotrope accumulation around the drug: the driving force for solubilization and minimum hydrotrope concentration for nicotinamide and urea. Phys Chem Chem Phys 2015; 17:8028-37. [DOI: 10.1039/c4cp05414h] [Citation(s) in RCA: 73] [Impact Index Per Article: 8.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
A rigorous statistical thermodynamic theory explains how urea and nicotinamide can solubilize hydrophobic drugs in water.
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Affiliation(s)
- Jonathan J. Booth
- York Structural Biology Laboratory
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
| | - Muhiadin Omar
- York Structural Biology Laboratory
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
| | - Steven Abbott
- Steven Abbott TCNF Ltd
- Suffolk IP1 3SZ
- UK
- School of Mechanical Engineering
- University of Leeds
| | - Seishi Shimizu
- York Structural Biology Laboratory
- Department of Chemistry
- University of York
- York YO10 5DD
- UK
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13
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Shimizu S, Booth JJ, Abbott S. Hydrotropy: binding models vs. statistical thermodynamics. Phys Chem Chem Phys 2013; 15:20625-32. [DOI: 10.1039/c3cp53791a] [Citation(s) in RCA: 60] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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14
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Poon GMK. Sequence discrimination by DNA-binding domain of ETS family transcription factor PU.1 is linked to specific hydration of protein-DNA interface. J Biol Chem 2012; 287:18297-307. [PMID: 22474303 DOI: 10.1074/jbc.m112.342345] [Citation(s) in RCA: 22] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022] Open
Abstract
PU.1 is an essential transcription factor in normal hematopoietic lineage development. It recognizes a large number of promoter sites differing only in bases flanking a core consensus of 5'-GGAA-3'. DNA binding is mediated by its ETS domain, whose sequence selectivity directly corresponds to the transactivational activity and frequency of binding sites for full-length PU.1 in vivo. To better understand the basis of sequence discrimination, we characterized its binding properties to a high affinity and low affinity site. Despite sharing a homologous structural framework as confirmed by DNase I and hydroxyl radical footprinting, the two complexes exhibit striking heterogeneity in terms of hydration properties. High affinity binding is destabilized by osmotic stress, whereas low affinity binding is insensitive. Dimethyl sulfate footprinting showed that the major groove at the core consensus is protected in the high affinity complex but accessible in the low affinity one. Finally, destabilization of low affinity binding by salt is in quantitative agreement with the number of phosphate contacts but is substantially attenuated in high affinity binding. These observations support a mechanism of sequence discrimination wherein specifically bound water molecules couple flanking backbone contacts with base-specific interactions in a sequestered cavity at the core consensus. The implications of this model with respect to other ETS paralogs are discussed.
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Affiliation(s)
- Gregory M K Poon
- Department of Pharmaceutical Sciences, Washington State University, Pullman, Washington 99164-6534, USA.
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15
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Kim JY, Kim S, Papp M, Park K, Pinal R. Hydrotropic solubilization of poorly water-soluble drugs. J Pharm Sci 2010; 99:3953-65. [PMID: 20607808 DOI: 10.1002/jps.22241] [Citation(s) in RCA: 77] [Impact Index Per Article: 5.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/08/2022]
Abstract
The solubilizing ability of two aromatic hydrotropes, N,N-diethylnicotinamide (DENA) and N,N-dimethylbenzamide (DMBA), was investigated using a set of 13 poorly soluble, structurally diverse drugs. The number of aromatic rings in the solute molecule has a very strong effect on the solubility enhancement produced by either hydrotrope. However, although solubility enhancements in the order of 1000- to 10,000-fold were obtained with each of the hydrotropic agents, important differences were found between the two. DMBA is more hydrophobic and undergoes more extensive self-association than DENA, as determined by vapor osmometry. As a result, DMBA is generally a more powerful solubilizer of hydrophobic drugs. DENA, on the other hand, is more polar and its self-association is essentially limited to dimer formation. However, despite being less hydrophobic, DENA is an extremely powerful solubilizer of paclitaxel, a highly hydrophobic compound. Such a result is attributed to the higher hydrogen bonding ability of DENA over DMBA and the very high hydrogen bonding ability of paclitaxel. These observations in turn illustrate the strong interplay between specific and hydrophobic interactions on the observed solubilization by hydrotropic agents.
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Affiliation(s)
- Ji Young Kim
- Department of Industrial and Physical Pharmacy, Purdue University, College of Pharmacy, 575 Stadium Mall Drive, West Lafayette, Indiana 47907-2091, USA
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16
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Cui Y, Xing C, Ran Y. Molecular Dynamics Simulations of Hydrotropic Solubilization and Self-Aggregation of Nicotinamide. J Pharm Sci 2010; 99:3048-59. [DOI: 10.1002/jps.22077] [Citation(s) in RCA: 29] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/06/2022]
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17
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Neumann MG, Schmitt CC, Prieto KR, Goi BE. The photophysical determination of the minimum hydrotrope concentration of aromatic hydrotropes. J Colloid Interface Sci 2007; 315:810-3. [PMID: 17681515 DOI: 10.1016/j.jcis.2007.07.020] [Citation(s) in RCA: 27] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/18/2007] [Revised: 06/22/2007] [Accepted: 07/09/2007] [Indexed: 11/30/2022]
Abstract
A method based on the aggregate to monomol emission ratio, I(aggr)/I(monomol), was used to determine the minimal hydrotropic concentration (MHC) of aromatic hydrotropes. The main advantage of this method is that it does not require the use of probes or other additives, which might disrupt the aggregation process. Also, it relies on spectrophotometric measurements, which are more sensitive and less arduous than others, like conductivity, light scattering and surface tension.
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Affiliation(s)
- Miguel G Neumann
- Instituto de Química de São Carlos, Universidade de São Paulo, Caixa Postal 780, 13560-970 São Carlos SP, Brazil.
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18
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Pandey E, Upadhyay SK. Hydrotropic Enhancement of Rate of Ninhydrin‐α‐Amino Acid Reaction: A Kinetic Study. J DISPER SCI TECHNOL 2006. [DOI: 10.1080/01932690500266993] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/25/2022]
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19
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Kitamura S, Fujimura T, Kohda S. Interaction between surface active drug (FK906:rennin inhibitor) and cyclodextrins in aqueous solution. J Pharm Sci 1999; 88:327-30. [PMID: 10052991 DOI: 10.1021/js980278d] [Citation(s) in RCA: 6] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
The aggregation behavior of FK906, which is a peptide like hypertensive agent, in aqueous solution was studied by static light scattering, 1H-nuclear magnetic resonance (NMR), and surface tension. These experiments showed a clear critical micelle concentration (cmc) at around 6.3 x 10(-3) to 1.3 x 10(-2) M of FK906 aqueous solution. The result of 1H NMR experiments revealed that FK906 aggregates primarily by hydrophobic interactions involving the benzyl moiety. The Debye plots from light-scattering studies showed that the apparent molecular weight of aggregated FK906 molecule is 1670 which corresponds to 2-3 molecules of FK906. The effect of alpha- and beta-cyclodextrins on the surface tension of FK906 aqueous solution was investigated. It appeared that the addition of alpha-cyclodextrin showed very small shift of cmc, but that of beta-cyclodextrin shifted the cmc to much higher concentration. The investigation on the surface tension of FK906 aqueous solution in the presence of beta-cyclodextrin indicated that FK906 forms a 1:1 complex with beta-cyclodextrin. On the basis of these experiments, it appears that beta-cyclodextrin has an ability to change the surface active property of FK906 in its aqueous solution. Therefore, it is expected that the addition of beta-cyclodextrin to FK906 aqueous solution may prevent the adsorption onto container walls and/or reduce the local irritancy.
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Affiliation(s)
- S Kitamura
- Analytical Research Laboratories, Fujisawa Pharmaceutical Co., Ltd. 1-6, Kashima 2-chome, Yodogawa-ku, Osaka 532-8514, Japan
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20
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Effect of Additives on the Cloud Points of Aqueous Solutions of Ethylene Oxide–Propylene Oxide–Ethylene Oxide Block Copolymers. J Colloid Interface Sci 1998. [DOI: 10.1006/jcis.1998.5456] [Citation(s) in RCA: 93] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2022]
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