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Kaschula CH, Tuveri R, Ngarande E, Dzobo K, Barnett C, Kusza DA, Graham LM, Katz AA, Rafudeen MS, Parker MI, Hunter R, Schäfer G. The garlic compound ajoene covalently binds vimentin, disrupts the vimentin network and exerts anti-metastatic activity in cancer cells. BMC Cancer 2019; 19:248. [PMID: 30894168 PMCID: PMC6425727 DOI: 10.1186/s12885-019-5388-8] [Citation(s) in RCA: 30] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/10/2018] [Accepted: 02/20/2019] [Indexed: 12/20/2022] Open
Abstract
BACKGROUND Garlic has been used for centuries for its flavour and health promoting properties that include protection against cancer. The vinyl disulfide-sulfoxide ajoene is one of the phytochemicals found in crushed cloves, hypothesised to act by S-thiolating reactive cysteines in target proteins. METHODS Using our fluorescently labelled ajoene analogue called dansyl-ajoene, ajoene's protein targets in MDA-MB-231 breast cancer cells were tagged and separated by 2D electrophoresis. A predominant band was identified by MALDI-TOF MS/MS to be vimentin. Target validation experiments were performed using pure recombinant vimentin protein. Computational modelling of vimentin bound to ajoene was performed using Schrödinger and pKa calculations by Epik software. Cytotoxicity of ajoene in MDA-MB-231 and HeLa cells was measured by the MTT assay. The vimentin filament network was visualised in ajoene-treated and non-treated cells by immunofluorescence and vimentin protein expression was determined by immunoblot. The invasion and migration activity was measured by wound healing and transwell assays using wildtype cells and cells in which the vimentin protein had been transiently knocked down by siRNA or overexpressed. RESULTS The dominant protein tagged by dansyl-ajoene was identified to be the 57 kDa protein vimentin. The vimentin target was validated to reveal that ajoene and dansyl-ajoene covalently bind to recombinant vimentin via a disulfide linkage at Cys-328. Computational modelling showed Cys-328 to be exposed at the termini of the vimentin tetramer. Treatment of MDA-MB-231 or HeLa cells with a non-cytotoxic concentration of ajoene caused the vimentin filament network to condense; and to increase vimentin protein expression. Ajoene inhibited the invasion and migration of both cancer cell lines which was found to be dependent on the presence of vimentin. Vimentin overexpression caused cells to become more migratory, an effect that was completely rescued by ajoene. CONCLUSIONS The garlic-derived phytochemical ajoene targets and covalently modifies vimentin in cancer cells by S-thiolating Cys-328. This interaction results in the disruption of the vimentin filament network and contributes to the anti-metastatic activity of ajoene in cancer cells.
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Affiliation(s)
- Catherine H. Kaschula
- Department of Chemistry and Polymer Science, Stellenbosch University, Stellenbosch, 7600 South Africa
| | - Rosanna Tuveri
- Department of Biomedical Science, University of Cagliari, 09042 Monserrato, Italy
| | - Ellen Ngarande
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
| | - Kevin Dzobo
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
- International Centre for Genetic Engineering and Biotechnology (ICGEB), UCT Medical Campus, Anzio Rd, Observatory, Cape Town, 7925 South Africa
| | - Christopher Barnett
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700 South Africa
| | - Daniel A. Kusza
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700 South Africa
| | - Lisa M. Graham
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
| | - Arieh A. Katz
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
| | - Mohamed Suhail Rafudeen
- Department of Molecular and Cell Biology, University of Cape Town, Rondebosch, Cape Town, 7700 South Africa
| | - M. Iqbal Parker
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
| | - Roger Hunter
- Department of Chemistry, University of Cape Town, Rondebosch, Cape Town, 7700 South Africa
| | - Georgia Schäfer
- Department of Integrative Biomedical Sciences and Institute of Infectious Disease and Molecular Medicine, Faculty of Health Sciences, University of Cape Town, Observatory, Cape Town, 7925 South Africa
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Michael Addition of Thiol Compounds on ω-Maleate Poly(ethylene oxide)s: Model Study for the “Site-Specific” Modification of Proteins. Macromol Res 2018. [DOI: 10.1007/s13233-018-6021-4] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
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Cui Y, Wang Y, Zhao L. Cysteine-Ag Cluster Hydrogel Confirmed by Experimental and Numerical Studies. SMALL (WEINHEIM AN DER BERGSTRASSE, GERMANY) 2015; 11:5118-5125. [PMID: 26248576 DOI: 10.1002/smll.201501245] [Citation(s) in RCA: 12] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 05/03/2015] [Revised: 06/05/2015] [Indexed: 06/04/2023]
Abstract
The native cysteine (Cys)-Ag3 cluster hydrogel is approved for the first time by both experimental and theoretical studies. From the detailed molecular structure and energy information, three factors are found to ensure the self-assembly of Cys and Ag3 , and result in the hydrogel. First, the Ag-S bonds make Cys and Ag3 form Cys-Ag3 -Cys monomer. Second, intermolecular hydrogen bonds between carboxyl groups of adjacent monomer push them self-assembled. Third, more monomer precisely self-assemble to produce the -[Cys-Ag3 -Cys]n multimer, e.g., a single molecular chain with the left-handed helix conformation, via a benign thermodynamic process. These multimers entangle together to form micro-network to trap water and produce hydorgel in situ. The hydrogen bonds of hydrogel are sensitive to thermal and proton stimuli, and the hydrogel presents lysosome targeting properties via fluorescent imaging with biocompatibility.
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Affiliation(s)
- Yanyan Cui
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Yaling Wang
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P. R. China
| | - Lina Zhao
- CAS Key Laboratory for Biomedical Effects of Nanomaterials and Nanosafety, Institute of High Energy Physics, Chinese Academy of Sciences, Beijing, 100049, P. R. China
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Choi CM, Heo J, Kim NJ. Binding selectivity of dibenzo-18-crown-6 for alkali metal cations in aqueous solution: A density functional theory study using a continuum solvation model. Chem Cent J 2012; 6:84. [PMID: 22873431 PMCID: PMC3464923 DOI: 10.1186/1752-153x-6-84] [Citation(s) in RCA: 34] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/01/2012] [Accepted: 08/01/2012] [Indexed: 12/02/2022] Open
Abstract
Background Dibenzo-18-crown-6 (DB18C6) exhibits the binding selectivity for alkali metal cations in solution phase. In this study, we investigate the main forces that determine the binding selectivity of DB18C6 for the metal cations in aqueous solution using the density functional theory (DFT) and the conductor-like polarizable continuum model (CPCM). Results The bond dissociation free energies (BDFE) of DB18C6 complexes with alkali metal cations (M+-DB18C6, M = Li, Na, K, Rb, and Cs) in aqueous solution are calculated at the B3LYP/6-311++G(d,p)//B3LYP/6-31 + G(d) level using the CPCM. It is found that the theoretical BDFE is the largest for K+-DB18C6 and decreases as the size of the metal cation gets larger or smaller than that of K+, which agrees well with previous experimental results. Conclusion The solvation energy of M+-DB18C6 in aqueous solution plays a key role in determining the binding selectivity of DB18C6. In particular, the non-electrostatic dispersion interaction between the solute and solvent, which depends strongly on the complex structure, is largely responsible for the different solvation energies of M+-DB18C6. This study shows that the implicit solvation model like the CPCM works reasonably well in predicting the binding selectivity of DB18C6 in aqueous solution.
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Affiliation(s)
- Chang Min Choi
- Department of Chemistry, Chungbuk National University, Chungbuk, 361-763, South Korea.
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Byun BJ, Kang YK. Conformational preferences and pK(a) value of selenocysteine residue. Biopolymers 2011; 95:345-53. [PMID: 21213257 DOI: 10.1002/bip.21581] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/17/2010] [Revised: 12/20/2010] [Accepted: 12/22/2010] [Indexed: 12/25/2022]
Abstract
The conformational preferences of the L-selenocysteine (Sec) dipeptides with selenol and selenolate groups (Ac-Sec-NHMe and Ac-Sec(-) -NHMe, respectively) and the apparent (i.e., macroscopic) pK(a) value of the Sec residue have been studied using the dispersion-corrected density functionals M06-2X and B2PLYP-D with the implicit solvation method in the gas phase and in water. In the gas phase, the backbone-to-backbone and/or side chain-to-backbone hydrogen bonds are found to contribute in stabilizing the most preferred conformations for the Sec and Sec(-) residues, as seen for the Cys and Cys(-) residues. However, the polyproline II-like conformations prevail over the conformations with the backbone-to-backbone hydrogen bonds in water because of the weakened hydrogen bonds by the favorable direct interactions between the backbone CO and HN groups and water molecules. The Sec and Sec(-) residues are found to adopt more various conformations than the Cys and Cys(-) residues in water, although the most preferred conformations of the neutral and/or anionic forms of the two residues are similar each other in the gas phase and in water. Using the statistically weighted free energies of the Sec and Sec(-) dipeptides in the gas phase and their solvation free energies, the pK(a) value of the Sec residue is estimated to be 5.47 at 25°C, which is in good agreement with the experimental value of 5.43 ± 0.02. It is found that the lower pK(a) value of the selenol side chain for the Sec residue by ∼3 units than the thiol side chain for the Cys residue is ascribed to the higher gas-phase acidity of the Sec residue.
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Affiliation(s)
- Byung Jin Byun
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk 361-763, Republic of Korea
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Kang YK, Byun BJ. Assessment of density functionals with long-range and/or empirical dispersion corrections for conformational energy calculations of peptides. J Comput Chem 2010; 31:2915-23. [DOI: 10.1002/jcc.21587] [Citation(s) in RCA: 44] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022]
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Liu S, Schauer CK, Pedersen LG. Molecular acidity: A quantitative conceptual density functional theory description. J Chem Phys 2010; 131:164107. [PMID: 19894927 DOI: 10.1063/1.3251124] [Citation(s) in RCA: 49] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022] Open
Abstract
Accurate predictions of molecular acidity using ab initio and density functional approaches are still a daunting task. Using electronic and reactivity properties, one can quantitatively estimate pKa values of acids. In a recent paper [S. B. Liu and L. G. Pedersen, J. Phys. Chem. A 113, 3648 (2009)], we employed the molecular electrostatic potential (MEP) on the nucleus and the sum of valence natural atomic orbital (NAO) energies for the purpose. In this work, we reformulate these relationships on the basis of conceptual density functional theory and compare the results with those from the thermodynamic cycle method. We show that MEP and NAO properties of the dissociating proton of an acid should satisfy the same relationships with experimental pKa data. We employ 27 main groups and first to third row transition metal-water complexes as illustrative examples to numerically verify the validity of these strong linear correlations. Results also show that the accuracy of our approach and that of the conventional method through the thermodynamic cycle are statistically similar.
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Affiliation(s)
- Shubin Liu
- Research Computing Center, University of North Carolina, Chapel Hill, North Carolina 27599-3420, USA.
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Kang YK, Park HS. Conformational preferences and cis-trans isomerization of L-3,4-dehydroproline residue. Biopolymers 2009; 92:387-98. [PMID: 19373924 DOI: 10.1002/bip.21203] [Citation(s) in RCA: 10] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Abstract
The conformational study of N-acetyl-N'-methylamide of L-3,4-dehydroproline (Ac-Dhp-NHMe, the Dhp dipeptide) is carried out using hybrid density functional methods with the self-consistent reaction field method in the gas phase and in solution (chloroform and water). The incorporation of a double bond between C(beta) and C(gamma) into the prolyl ring results in the puckering, backbone population, and barriers to prolyl cis-trans isomerization different from those of the Pro dipeptide. For local minima of the Dhp dipeptide in the gas phase and in water, the C(beta)-C(gamma) bonds become shorter by approximately 0.2 A and the bond angles C(alpha)-C(beta)-C(gamma) and C(beta)-C(gamma)-C(delta) are widened by approximately 8 degrees than those of the Pro dipeptide, and the puckering amplitude is computed to be 0.01-0.07 A, indicating that the 3,4-dehydroprolyl ring is quite less puckered. However, polyproline-like conformations become preferred and the relative stability of the conformation tC with a C(7) intramolecular hydrogen bond decreases as the solvent polarity increases, as found for the Pro dipeptide. The barriers to cis-trans isomerization of the Ac-Dhp peptide bond increase with the increase of solvent polarity and the isomerization is likely to proceed through the clockwise rotation in water, as found for the prolyl peptide bond. The hydrogen bond between the prolyl nitrogen and the following amide N-H group seems to contribute in stabilizing the transition state structures.
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Affiliation(s)
- Young Kee Kang
- Department of Chemistry, Chungbuk National University, Cheongju, Chungbuk, Republic of Korea.
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Lee JY, Lee H, Lim JY, Yoo SE, Kang NS. Ionic interactions for substituted MCH1R inhibitors studied by pKa values. Bioorg Med Chem Lett 2009; 19:4376-9. [DOI: 10.1016/j.bmcl.2009.05.075] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/30/2009] [Revised: 05/12/2009] [Accepted: 05/20/2009] [Indexed: 10/20/2022]
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