1
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Holman A, Quinn K, Kumar R, Kmiecik S, Ali A, Kurouski D. Fatty Acids Reverse the Supramolecular Chirality of Insulin Fibrils. J Phys Chem Lett 2023; 14:6935-6939. [PMID: 37498215 PMCID: PMC10863027 DOI: 10.1021/acs.jpclett.3c01527] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2023] [Accepted: 07/19/2023] [Indexed: 07/28/2023]
Abstract
Long-chain unsaturated and polyunsaturated fatty acids (LCUFAs and LCPUFAs, respectively) are the essential components of phospholipids and sphingolipids, major building blocks of plasma and organelle membranes. These molecules are also involved in cell signaling and energy metabolism. Hence, both LCUFAs and LCPUFAs are broadly used as food supplements. However, the role of these fatty acids (FAs) in the self-assembly of misfolded proteins remains unclear. In this study, we investigated the effect of LCUFAs and LCPUFAs, as well as their saturated analogue, on insulin aggregation. Using vibrational circular dichroism, we found that all analyzed FAs reversed the supramolecular chirality of insulin fibrils. Molecular dynamics simulations showed that strong hydrophobic interactions were formed between the long aliphatic tails of FAs and hydrophobic amino acid residues of insulin. We infer that such insulin:FA complexes had different self-assembly mechanisms compared to that of insulin alone, which resulted in the observed reversal of the supramolecular chirality of the amyloid fibrils.
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Affiliation(s)
- Aidan
P. Holman
- Department
of Entomology, Texas A&M University, College Station, Texas 77843, United States
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
| | | | - Rakesh Kumar
- Biological
and Chemical Research Center, University
of Warsaw, Warsaw 02-089, Poland
| | - Sebastian Kmiecik
- Biological
and Chemical Research Center, University
of Warsaw, Warsaw 02-089, Poland
| | - Abid Ali
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
| | - Dmitry Kurouski
- Department
of Biochemistry and Biophysics, Texas A&M
University, College
Station, Texas 77843, United States
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2
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Argudo PG, Contreras-Montoya R, Álvarez de Cienfuegos L, Martín-Romero MT, Camacho L, Giner-Casares JJ. Optimization of Amino Acid Sequence of Fmoc-Dipeptides for Interaction with Lipid Membranes. J Phys Chem B 2019; 123:3721-3730. [DOI: 10.1021/acs.jpcb.9b01132] [Citation(s) in RCA: 6] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Affiliation(s)
- Pablo G. Argudo
- Departamento de Química Física y T. Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Facultad de Ciencias, Universidad de Córdoba (UCO), Campus de Rabanales, Ed. Marie Curie, E-14071 Córdoba, Spain
| | - Rafael Contreras-Montoya
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada (UGR), C. U. Fuentenueva, Granada E-18071, Spain
| | - Luis Álvarez de Cienfuegos
- Departamento de Química Orgánica, Facultad de Ciencias, Universidad de Granada (UGR), C. U. Fuentenueva, Granada E-18071, Spain
| | - María T. Martín-Romero
- Departamento de Química Física y T. Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Facultad de Ciencias, Universidad de Córdoba (UCO), Campus de Rabanales, Ed. Marie Curie, E-14071 Córdoba, Spain
| | - Luis Camacho
- Departamento de Química Física y T. Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Facultad de Ciencias, Universidad de Córdoba (UCO), Campus de Rabanales, Ed. Marie Curie, E-14071 Córdoba, Spain
| | - Juan J. Giner-Casares
- Departamento de Química Física y T. Aplicada, Instituto Universitario de Investigación en Química Fina y Nanoquímica IUIQFN, Facultad de Ciencias, Universidad de Córdoba (UCO), Campus de Rabanales, Ed. Marie Curie, E-14071 Córdoba, Spain
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3
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Panja S, Adams DJ. Maintaining homogeneity during a sol-gel transition by an autocatalytic enzyme reaction. Chem Commun (Camb) 2019; 55:47-50. [PMID: 30507994 DOI: 10.1039/c8cc08501c] [Citation(s) in RCA: 26] [Impact Index Per Article: 5.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/28/2023]
Abstract
Kinetic control over supramolecular gelation by increasing the pH can be achieved using an enzymatic reaction. This method allows us to produce homogeneous hydrogels with superior and improved mechanical properties as compared to gels obtained from simple addition of base.
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Affiliation(s)
- Santanu Panja
- School of Chemistry, University of Glasgow, Glasgow, G12 8QQ, UK.
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4
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Argudo PG, Contreras-Montoya R, Álvarez de Cienfuegos L, Martín-Romero MT, Camacho L, Giner-Casares JJ. Subtle chemical modification for enrichment of Fmoc-amino acid at a phospholipid interface. RSC Adv 2019; 9:37188-37194. [PMID: 35542247 PMCID: PMC9075599 DOI: 10.1039/c9ra03896e] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/23/2019] [Accepted: 11/06/2019] [Indexed: 11/24/2022] Open
Abstract
Amino acids including the Fmoc group (9-fluorenylmethyloxycarbonyl) are bioinspired molecules that display intriguing features in self-assembly and biological applications. The influence of a delicate chemical modification between Fmoc-F and Fmoc-Y on the interaction with a phospholipid surface was analyzed. Langmuir monolayers of the 1,2-dimyristoyl-sn-glycero-3-phosphate (DMPA) phospholipid were used to mimic the eukaryotic cell membrane. In situ Brewster angle microscopy and UV-vis reflection spectroscopy provided insights on the effect of the Fmoc-amino acid derivatives on the DMPA phospholipid. The formation of H-bonds between the Fmoc-Y and the DMPA molecules was assessed, demonstrating the crucial role of the hydroxyl group of Fmoc-Y in enhancing the interaction with biosurfaces. A modest chemical modification of the Fmoc-amino acids led to enhanced interaction with a model surface for biomembrane.![]()
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Affiliation(s)
- Pablo G. Argudo
- Departamento de Química Física y T. Aplicada
- Instituto Universitario de Investigación en Química Fina y Nanoquímica IUNAN
- Facultad de Ciencias
- Universidad de Córdoba (UCO)
- E-14071 Córdoba
| | - Rafael Contreras-Montoya
- Departamento de Química Orgánica
- Facultad de Ciencias
- Universidad de Granada, (UGR)
- E-18071 Granada
- Spain
| | | | - María T. Martín-Romero
- Departamento de Química Física y T. Aplicada
- Instituto Universitario de Investigación en Química Fina y Nanoquímica IUNAN
- Facultad de Ciencias
- Universidad de Córdoba (UCO)
- E-14071 Córdoba
| | - Luis Camacho
- Departamento de Química Física y T. Aplicada
- Instituto Universitario de Investigación en Química Fina y Nanoquímica IUNAN
- Facultad de Ciencias
- Universidad de Córdoba (UCO)
- E-14071 Córdoba
| | - Juan J. Giner-Casares
- Departamento de Química Física y T. Aplicada
- Instituto Universitario de Investigación en Química Fina y Nanoquímica IUNAN
- Facultad de Ciencias
- Universidad de Córdoba (UCO)
- E-14071 Córdoba
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5
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Gahane AY, Ranjan P, Singh V, Sharma RK, Sinha N, Sharma M, Chaudhry R, Thakur AK. Fmoc-phenylalanine displays antibacterial activity against Gram-positive bacteria in gel and solution phases. SOFT MATTER 2018; 14:2234-2244. [PMID: 29517792 DOI: 10.1039/c7sm02317k] [Citation(s) in RCA: 61] [Impact Index Per Article: 10.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 05/21/2023]
Abstract
In the quest for new antimicrobial materials, hydrogels of Fmoc-protected peptides and amino acids have gained momentum due to their ease of synthesis and cost effectiveness; however, their repertoire is currently limited, and the mechanistic details of their function are not well understood. Herein, we report the antibacterial activity of the hydrogel and solution phases of Fmoc-phenylalanine (Fmoc-F) against a variety of Gram-positive bacteria including methicillin-resistant Staphylococcus aureus (MRSA). Fmoc-F, a small molecule hydrogelator, reduces the bacterial load both in vitro and in the skin wound infections of mice. The antibacterial activity of Fmoc-F is predominantly due to its release from the hydrogel. Fmoc-F shows surfactant-like properties with critical micelle concentration nearly equivalent to its minimum bactericidal concentration. Similar to Fmoc-F, some Fmoc-conjugated amino acids (Fmoc-AA) have also shown antibacterial effects that are linearly correlated with their surfactant properties. At low concentrations, where Fmoc-F does not form micelles, it inhibits bacterial growth by entering the cell and reducing the glutathione levels. However, at higher concentrations, Fmoc-F triggers oxidative and osmotic stress and, alters the membrane permeabilization and integrity, which kills Gram-positive bacteria. Herein, we proposed the use of the Fmoc-F hydrogel and its solution for several biomedical applications. This study will open up new avenues to enhance the repertoire of Fmoc-AA to act as antimicrobial agents and improve their structure-activity relationship.
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Affiliation(s)
- Avinash Y Gahane
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Pritish Ranjan
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Virender Singh
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
| | - Raj K Sharma
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014, India
| | - Neeraj Sinha
- Centre of Biomedical Research, SGPGIMS Campus, Lucknow 226014, India
| | - Mandeep Sharma
- DGCN College of Veterinary and Animal Sciences, CSK HPKV, Palampur-176062, India
| | - Rama Chaudhry
- All India Institute of Medical Sciences, New Delhi, India
| | - Ashwani K Thakur
- Department of Biological Sciences and Bioengineering, Indian Institute of Technology Kanpur, Kanpur 208016, India.
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6
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Quantum chemical analysis of electronic structure and bonding aspects of choline based ionic liquids. J Mol Liq 2018. [DOI: 10.1016/j.molliq.2017.11.080] [Citation(s) in RCA: 14] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
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7
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Kurouski D. Advances of Vibrational Circular Dichroism (VCD) in bioanalytical chemistry. A review. Anal Chim Acta 2017; 990:54-66. [PMID: 29029743 PMCID: PMC10389559 DOI: 10.1016/j.aca.2017.08.014] [Citation(s) in RCA: 44] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/06/2016] [Revised: 08/08/2017] [Accepted: 08/09/2017] [Indexed: 12/26/2022]
Abstract
Vibrational Circular Dichroism (VCD) is a unique and relatively new spectroscopic technique that is capable of determining an absolute configuration of chiral molecules. VCD can be also used to determine structure of large macromolecules. This review highlights the most recent advances of VCD in bioanalytical chemistry. It shows that VCD is capable of unraveling supramolecular organization of peptides, proteins, saccharides, glycerophospholipids, polypeptide microcrystals, as well as amyloid fibrils and DNA. This review also demonstrates how VCD can be utilized to explore molecule-molecule interactions that determine mechanisms of chiral separations in chromatography. It aims to attract attention of scientists from all different research areas demonstrating the strength and capability of this very powerful spectroscopic technique.
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Affiliation(s)
- Dmitry Kurouski
- Department Biochemistry and Biophysics, Texas A&M University, 2128 TAMU, College Station, TX 77843, USA.
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8
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Raghavan V, Polavarapu PL. Specific optical rotation is a versatile tool for the identification of critical micelle concentration and micellar growth of tartaric acid-based diastereomeric amphiphiles. Chirality 2017; 29:836-846. [PMID: 28991388 DOI: 10.1002/chir.22767] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/14/2017] [Revised: 08/14/2017] [Accepted: 08/29/2017] [Indexed: 11/09/2022]
Abstract
Four novel tartaric acid-based diastereomeric chiral amphiphiles, two being enantiomers of the other two, have been synthesized and investigated using chiroptical spectroscopic methods, along with tensiometry and dynamic light scattering experiments. We found that an inflection point in specific optical rotation (SOR) values at ~0.32 mM corresponds to the critical micelle concentration (CMC). The increase in magnitude of SOR values beyond CMC corresponds to the growth of aggregates. For enantiomers, oppositely signed SOR values were observed, ruling out the possibility for the presence of aggregation size mediated artefacts. SOR values did not exhibit concentration dependence for a chiral tartaric acid based non-aggregating analogue further establishing the absence of artefacts or anomalous interaction of tartaric acid based head group with solvent. Electronic circular dichroism spectra showed no significant changes in band positions or intensities with concentration. Due to the requirement for higher concentrations (~200 mM) needed to obtain vibrational circular dichroism spectra, these measurements are not found to be useful for studying concentration dependent properties of chiral amphiphiles.
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Affiliation(s)
- Vijay Raghavan
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee, USA
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9
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Kononov LO, Fedina KG, Orlova AV, Kondakov NN, Abronina PI, Podvalnyy NM, Chizhov AO. Bimodal concentration-dependent reactivity pattern of a glycosyl donor: Is the solution structure involved? Carbohydr Res 2016; 437:28-35. [PMID: 27883907 DOI: 10.1016/j.carres.2016.11.009] [Citation(s) in RCA: 21] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/18/2016] [Revised: 11/10/2016] [Accepted: 11/10/2016] [Indexed: 11/30/2022]
Abstract
Changes in concentration (0.001-0.1 M) of an arabinofuranosyl donor (1) have been shown to modulate the temperature T at which activation of 1 occurs (from -23 °C to +7 °C), the reaction time (from 1.5 h to 3 days) and the yield of the disaccharide formed (from 14% to 82%). At concentrations exceeding 0.01 M, these parameters, as well as the specific optical rotation of the solution of 1, virtually do not depend on concentration suggesting formation of reacting species (supramers) of glycosyl donor with similar structures, hence reactivities, but considerably different from those formed in more dilute solutions. The found critical concentration (0.01 M) separates two concentration ranges of reaction solutions corresponding to two types of solution structure that are featured by the presence of fundamentally different supramers of glycosyl donor, which have distinct chemical properties. These results allow a fresh look at the problems of reactivity of chemical compounds and selectivity of the reactions in which they participate.
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Affiliation(s)
- Leonid O Kononov
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation.
| | - Ksenia G Fedina
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
| | - Anna V Orlova
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
| | - Nikolay N Kondakov
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
| | - Polina I Abronina
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
| | - Nikita M Podvalnyy
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
| | - Alexander O Chizhov
- N. D. Zelinsky Institute of Organic Chemistry of the Russian Academy of Sciences, Leninsky Prosp., 47, 119991, Moscow, Russian Federation
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10
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Covington CL, Polavarapu PL. Concentration Dependent Specific Rotations of Chiral Surfactants: Experimental and Computational Studies. J Phys Chem A 2016; 120:5715-25. [PMID: 27355395 DOI: 10.1021/acs.jpca.6b05039] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
Recent experimental studies have shown unexpected chiroptical response from some chiral surfactant molecules, where the specific rotations changed significantly as a function of concentration. To establish a theoretical understanding of this experimentally observed phenomena, a novel methodology for studying chiral surfactants via combined molecular dynamics (MD) and quantum mechanical (QM) calculations is presented. MD simulations on the +10 000 atom surfactant systems have been performed using MD and QM/molecular mechanics (MM) approaches. QM calculations performed on MD snapshots coupled with extensive analysis on lauryl ester of phenylalanine (LEP) surfactant system indicate that the experimentally observed variation of specific rotation with concentration may be due to the conformational differences of the surfactant monomers in the aggregates. Though traditional MM simulations did not show significant differences in the conformer populations, QM/MM simulations using the forces derived from the PM6 method did predict conformational differences between aggregated and nonaggregated LEP molecules, which is consistent with experimental data. Additionally the electrostatic environment of charged surfactants may also be important, since dramatic changes in the Boltzmann populations of surfactant monomers can be noted in the presence of an electric field generated by the chiral ionic aggregates.
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Affiliation(s)
- Cody L Covington
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
| | - Prasad L Polavarapu
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
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11
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Reddy SMM, Shanmugam G, Duraipandy N, Kiran MS, Mandal AB. An additional fluorenylmethoxycarbonyl (Fmoc) moiety in di-Fmoc-functionalized L-lysine induces pH-controlled ambidextrous gelation with significant advantages. SOFT MATTER 2015; 11:8126-8140. [PMID: 26338226 DOI: 10.1039/c5sm01767j] [Citation(s) in RCA: 57] [Impact Index Per Article: 6.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
In recent years, several fluorenylmethoxycarbonyl (Fmoc)-functionalized amino acids and peptides have been used to construct hydrogels, which find a wide range of applications. Although several hydrogels have been prepared from mono Fmoc-functionalized amino acids, herein, we demonstrate the importance of an additional Fmoc-moiety in the hydrogelation of double Fmoc-functionalized L-lysine [Fmoc(Nα)-L-lysine(NεFmoc)-OH, (Fmoc-K(Fmoc))] as a low molecular weight gelator (LMWG). Unlike other Fmoc-functionalized amino acid gelators, Fmoc-K(Fmoc) exhibits pH-controlled ambidextrous gelation (hydrogelation at different pH values as well as organogelation), which is significant among the gelators. Distinct fibrous morphologies were observed for Fmoc-K(Fmoc) hydrogels formed at different pH values, which are different from organogels in which Fmoc-K(Fmoc) showed bundles of long fibers. In both hydrogels and organogels, the self-assembly of Fmoc-K(Fmoc) was driven by aromatic π-π stacking and hydrogen bonding interactions, as evidenced from spectroscopic analyses. Characterization of Fmoc-K(Fmoc) gels using several biophysical methods indicates that Fmoc-K(Fmoc) has several advantages and significant importance as a LMWG. The advantages of Fmoc-K(Fmoc) include pH-controlled ambidextrous gelation, pH stimulus response, high thermal stability (∼100 °C) even at low minimum hydrogelation concentration (0.1 wt%), thixotropic property, high kinetic and mechanical stability, dye removal properties, cell viability to the selected cell type, and as a drug carrier. While single Fmoc-functionalized L-lysine amino acids failed to exhibit gelation under similar experimental conditions, the pH-controlled ambidextrous gelation of Fmoc-K(Fmoc) demonstrates the benefit of a second Fmoc moiety in inducing gelation in a LMWG. We thus strongly believe that the current findings provide a lead to construct or design various new synthetic Fmoc-based LMW organic gelators for several potential applications.
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Affiliation(s)
- Samala Murali Mohan Reddy
- Bioorganic Laboratory, Council of Scientific and Industrial Research - Central Leather Research Institute, Adyar, Chennai 600020, India.
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12
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Sato H, Yajima T, Yamagishi A. Chiroptical Studies on Supramolecular Chirality of Molecular Aggregates. Chirality 2015; 27:659-66. [DOI: 10.1002/chir.22482] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.1] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/29/2015] [Revised: 06/04/2015] [Accepted: 06/08/2015] [Indexed: 12/27/2022]
Affiliation(s)
- Hisako Sato
- Graduated of Science and Engineering; Ehime University; Matsuyama Japan
| | - Tomoko Yajima
- Department of Chemistry; Ochanomizu University; Tokyo Japan
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13
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Draper ER, Morris KL, Little MA, Raeburn J, Colquhoun C, Cross ER, McDonald TO, Serpell LC, Adams DJ. Hydrogels formed from Fmoc amino acids. CrystEngComm 2015. [DOI: 10.1039/c5ce00801h] [Citation(s) in RCA: 70] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/22/2023]
Abstract
A number of Fmoc amino acids can be effective low molecular weight hydrogelators; we compare single crystal structures to fibre X-ray diffraction data.
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Affiliation(s)
| | | | - Marc A. Little
- Department of Chemistry
- University of Liverpool
- Liverpool, UK
| | - Jaclyn Raeburn
- Department of Chemistry
- University of Liverpool
- Liverpool, UK
| | | | - Emily R. Cross
- Department of Chemistry
- University of Liverpool
- Liverpool, UK
| | | | | | - Dave J. Adams
- Department of Chemistry
- University of Liverpool
- Liverpool, UK
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14
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Li T, Kalloudis M, Cardoso AZ, Adams DJ, Clegg PS. Drop-casting hydrogels at a liquid interface: the case of hydrophobic dipeptides. LANGMUIR : THE ACS JOURNAL OF SURFACES AND COLLOIDS 2014; 30:13854-13860. [PMID: 24842147 DOI: 10.1021/la501182t] [Citation(s) in RCA: 16] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
Hydrophobic dipeptide molecules have been induced to self-assemble into thin interfacial films at the air-water interface via drop-casting. The mechanism involves fiberlike strands, which exist in the high-pH spreading solvent, becoming intertwined at the surface of a low-pH subphase. Atomic force microscopy (AFM) reveals that the strands are ∼40 nm wide and ∼20 nm high and are woven together to form layers that can be up to ∼800 nm thick. The use of Thioflavin T (ThT) fluorescence suggests that the dipeptides are ordered in a β-sheet configuration irrespective of whether they form an interfacial film, while Fourier transform infrared spectroscopy (FTIR) shows the protonation effect for those which do form an interfacial film. The entanglement between protonated strands results in the formation of an elastic sheet. The interfacial films buckled under compression in a Langmuir trough and have the ability to convey long-term stability to large air bubbles.
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Affiliation(s)
- Tao Li
- School of Physics and Astronomy, University of Edinburgh , Mayfield Road, Edinburgh EH9 3JZ, U.K
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15
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Abbate S, Passarello M, Lebon F, Longhi G, Ruggirello A, Turco Liveri V, Viani F, Castiglione F, Mendola D, Mele A. Chiroptical Phenomena in Reverse Micelles: The Case of (1R,2S)-Dodecyl (2-hydroxy-1-methyl-2-phenylethyl)dimethylammonium Bromide (DMEB). Chirality 2014; 26:532-8. [DOI: 10.1002/chir.22309] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.9] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/06/2013] [Accepted: 01/23/2014] [Indexed: 11/10/2022]
Affiliation(s)
- Sergio Abbate
- Dipartimento di Medicina Molecolare e Traslazionale; Università di Brescia; Brescia Italy
- Consorzio Interuniversitario Scienze Fisiche della Materia; Roma Italy
| | - Marco Passarello
- Dipartimento di Medicina Molecolare e Traslazionale; Università di Brescia; Brescia Italy
- Department of Chemistry; Materials and Chemical Engineering “G. Natta,” Politecnico di Milano; Milano Italy
| | - France Lebon
- Dipartimento di Medicina Molecolare e Traslazionale; Università di Brescia; Brescia Italy
- Consorzio Interuniversitario Scienze Fisiche della Materia; Roma Italy
| | - Giovanna Longhi
- Dipartimento di Medicina Molecolare e Traslazionale; Università di Brescia; Brescia Italy
- Consorzio Interuniversitario Scienze Fisiche della Materia; Roma Italy
| | - Angela Ruggirello
- Dipartimento di Chimica; Università degli Studi di Palermo; Palermo Italy
- ISMN; Istituto per lo Studio dei Materiali Nanostrutturati; Palermo Italy
| | - Vincenzo Turco Liveri
- Dipartimento di Chimica; Università degli Studi di Palermo; Palermo Italy
- ISMN; Istituto per lo Studio dei Materiali Nanostrutturati; Palermo Italy
| | - Fiorenza Viani
- Istituto di Chimica del Riconoscimento Molecolare - CNR; Milano Italy
| | - Franca Castiglione
- Department of Chemistry; Materials and Chemical Engineering “G. Natta,” Politecnico di Milano; Milano Italy
| | - Daniele Mendola
- Department of Chemistry; Materials and Chemical Engineering “G. Natta,” Politecnico di Milano; Milano Italy
| | - Andrea Mele
- Department of Chemistry; Materials and Chemical Engineering “G. Natta,” Politecnico di Milano; Milano Italy
- Istituto di Chimica del Riconoscimento Molecolare - CNR; Milano Italy
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16
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Orlova AV, Andrade RR, da Silva CO, Zinin AI, Kononov LO. Polarimetry as a tool for the study of solutions of chiral solutes. Chemphyschem 2013; 15:195-207. [PMID: 24357041 DOI: 10.1002/cphc.201300894] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/24/2013] [Indexed: 11/06/2022]
Abstract
Optical rotation of aqueous solutions of D-levoglucosan was studied experimentally in the 0.03-4.0 mol L(-1) concentration range and a nonlinear concentration dependence of specific optical rotation (SR) was revealed. Discontinuities observed in the concentration plot of SR (at 0.1, 0.3, 0.5, 1.0, and 2.0 mol L(-1)) are well correlated with those found by static and dynamic light scattering and identify concentration ranges in which different solution domains (supramers) may exist. The average SR experimental value for a D-levoglucosan aqueous solution ([α]D(28) -58.5±8.7 deg dm(-1) cm(-3) g(-1)) was found to be in good agreement with values obtained by theoretical calculation (TD-DFT/GIAO) of SR for 15 different conformers revealed by conformational sampling at the PCM/B3LYP/6-311++G(2d,2p)//B3LYP/6-31+G(d,p) level, which were shown to be strongly affected by the solvation microenvironment (0, 1, 2, and 3 explicit solvent molecules considered) due to local geometrical changes induced in the solute molecule. This exceptionally high sensitivity of SR makes polarimetry a unique method capable of sensing changes in the structure of supramers detected in this study.
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Affiliation(s)
- Anna V Orlova
- N. K. Kochetkov Laboratory of Carbohydrate Chemistry, N. D. Zelinsky Institute of Organic Chemistry, Russian Academy of Sciences, Leninsky prospect 47, 11991 Moscow (Russian Federation), Fax: (+7) 499-135-5328
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Vijay R, Polavarapu PL. Molecular Structural Transformations Induced by Spatial Confinement in Barium Fluoride Cells. J Phys Chem A 2013; 117:14086-94. [DOI: 10.1021/jp409770w] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Affiliation(s)
- R. Vijay
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
| | - Prasad L. Polavarapu
- Department of Chemistry, Vanderbilt University, Nashville, Tennessee 37235, United States
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Vijay R, Baskar G, Mandal AB, Polavarapu PL. Unprecedented relationship between the size of spherical chiral micellar aggregates and their specific optical rotations. J Phys Chem A 2013; 117:3791-7. [PMID: 23574486 DOI: 10.1021/jp401544g] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/01/2023]
Abstract
Transmission electron microscopy (TEM) images and fluorescence quenching methods indicated that lauryl ester of L-phenylalanine (LEP) and lauryl ester of L-tyrosine (LET) form spherical chiral micelles in the 50-200 mM range and their size increases with concentration. The number of molecules present in these spherical chiral aggregates varied from 80 to 160 for LEP and 80-100 for LET. The specific optical rotation, representing circular birefringence, for LEP at 405 nm and 32 °C is found to increase linearly from 37 deg cc g(-1) dm(-1) for an isolated molecule to 56 deg cc g(-1) dm(-1) for ∼200 nm size aggregate. A similar trend was found for temperatures up to 70 °C and at other visible wavelengths. A linear relation between specific optical rotation and the size of aggregate is also observed for LET. Circular dichroism, as measured in both the visible and infrared wavelength regions, however did not reveal any concentration dependent changes. The unique sensitivity uncovered for specific optical rotation as a function of the size of spherical chiral aggregates is unprecedented and opens new areas of enquiry for physical chemists.
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Affiliation(s)
- R Vijay
- Department of Chemistry, Vanderbilt University , Nashville, Tennessee 37235, United States
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