Article
Chemistry, Physical
Kevin Scholten, Christian Merten
Summary: The conformational preferences of peptides are determined by hydrogen bonding interactions, which can be studied using VCD spectroscopy. In chloroform, the peptide's conformational preferences can be described well by assuming implicit solvation effects. In DMSO-d(6), explicit solvation structures are required to match the experimental data. Structures with intramolecular hydrogen bonds contribute to the conformational distribution only when there is no strong interaction with the solvent.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Jennifer Dupont, Regis Guillotb, Valeria Lepere, Anne Zehnacker
Summary: The structures of diastereomer diketopiperazine dipeptides cyclo(LTyr-LPhe) and cyclo-(DTyr-LPhe) were studied in the gas phase using resonance-enhanced two-photon ionization, IR/UV double resonance spectroscopy, and quantum chemical calculation. Both diastereomers exhibit two conformations with slight differences in weak CH···ir and NH···ir interactions. The crystal structure and vibrational circular dichroism spectrum were determined, with quantum chemical calculation shedding light on structural modifications between the gas phase and the solid state.
JOURNAL OF MOLECULAR STRUCTURE
(2022)
Article
Chemistry, Physical
Tao Wu, Josef Kapitan, Petr Bour
Summary: Chiral metal complexes have rich photophysical properties and are important for various applications. This study combines experimental and computational approaches to investigate the energies and transition moments of excited electronic states in two chiral metal complexes. The experimental protocol involves multiple techniques, and a formula for subtracting interfering effects is provided. Density functional theory calculations are used to analyze the spectra and reveal the geometric and electronic structures of the molecules. This insight into molecular electronic states can be useful for understanding and manipulating the photochemical properties of metal-containing complexes, biomolecules, and supramolecules.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Physical
Clemens Mueller, Christian Merten
Summary: Infrared and vibrational circular dichroism (VCD) spectra are highly sensitive to solute-solvent interactions. The study investigates the effects of solvents on the IR and VCD spectra of small peptides, which possess hydrogen bonding donor sites. It is found that the presence of multiple hydrogen bonding sites in molecules with multiple conformers necessitates the consideration of mixed solvation states to accurately describe the experimental spectra.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Spectroscopy
Natalia Hachlica, Aleksandra Kolodziejczyk, Michal Rawski, Marcin Gorecki, Aleksandra Wajda, Agnieszka Kaczor
Summary: Environmental factors can compete against the templated growth of amyloid fibrils, and the structural indeterminism originates from deeper levels of the fibril structure.
SPECTROCHIMICA ACTA PART A-MOLECULAR AND BIOMOLECULAR SPECTROSCOPY
(2024)
Article
Chemistry, Multidisciplinary
Aleksandra Kolodziejczyk, Laurence A. Nafie, Aleksandra Wajda, Agnieszka Kaczor
Summary: Amyloid fibrils exhibit multi-layered chiral supramolecular structures and are highly sensitive to vibrational circular dichroism (VCD) for fibril formation. In this study, we demonstrate an exceptionally large enhancement of Raman optical activity (ROA) signal in mature amyloid fibrils and their prefibrillar states. This enhanced ROA signal is observed in fibrils of different proteins, indicating a possible general phenomenon. The ROA signal appears earlier than VCD and provides access to a broader range of vibrations, suggesting its potential utility for analyzing amyloid fibrils.
CHEMICAL COMMUNICATIONS
(2023)
Article
Multidisciplinary Sciences
Ruiwen Ding, Jianxi Ying, Yufen Zhao
Summary: The rapid quantitative analysis of single chiral amino acid using CD and LC methods provided accurate results with errors less than 10%. Additionally, this method can also be applied to the quantification of non-amino acid chiral molecules.
ROYAL SOCIETY OPEN SCIENCE
(2021)
Article
Biochemistry & Molecular Biology
Jose L. Neira, Ana Camara-Artigas, Jose Gines Hernandez-Cifre, Maria Grazia Ortore
Summary: The research focused on the conformational characterization of Bacillus subtilis HPrK/P, revealing that the protein exhibited high conformational stability at pH 7.0, strong pH sensitivity, and denaturation through an oligomeric intermediate in guanidinium hydrochloride denaturation.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2021)
Article
Chemistry, Physical
Yanqing Yang, Joseph Cheramy, Yunjie Xu
Summary: The conformational landscape and aggregation behavior of THFA were investigated using MI-VCD, revealing unusual structures formed in a cold rare gas matrix. Experiment results showed the presence of trans and cis conformers of THFA, as well as the formation of a few hundred stable binary conformers. This study highlights the power of MI-VCD spectroscopy in identifying unique structures in a controlled environment.
Article
Chemistry, Physical
Hisako Sato, Kazuyoshi Takimoto, Akihiko Yamagishi, Jun Yoshida, Mitsuo Hara
Summary: Solid state vibrational circular dichroism (SD-VCD) spectra were recorded on intercalation compounds of sodium montmorillonite with a chiral iridium(III) complex. The VCD signals were sensitive to molecular interactions in adsorption layers and signal enhancement was achieved through coherent delocalization of vibrational motions. Theoretical simulations were used to propose models of molecular packing.
APPLIED CLAY SCIENCE
(2022)
Article
Chemistry, Physical
Aidan P. Holman, Kimberly Quinn, Rakesh Kumar, Sebastian Kmiecik, Abid Ali, Dmitry Kurouski
Summary: Long-chain unsaturated and polyunsaturated fatty acids are important components of cell membranes and are involved in cell signaling and metabolism. They are widely used as food supplements but their role in the self-assembly of misfolded proteins is still unclear.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Guojie Li, Dan Li, Mutasem Alshalalfeh, Joseph Cheramy, Hui Zhang, Yunjie Xu
Summary: Two transition metal complexes were synthesized with a tetradentate Schiff-base ligand, and their stereochemical properties were investigated using a combined experimental and theoretical approach. Multiple spectroscopic techniques, including IR, VCD, UV-Vis, ECD, Raman, and eCP-Raman spectroscopies, were utilized to analyze the ligand and the metal complexes. The results showed good agreement between the experimental and simulated spectra, allowing for the identification of three main ligand conformers and the determination of the helicity of the metal complexes.
Article
Biochemistry & Molecular Biology
Mai Shiozaki, Tadashi Mizoguchi, Jiro Harada, Mitsuaki Hirose, Hitoshi Tamiaki
Summary: In this study, chiral-phase high-performance liquid chromatography (HPLC) was used to separate (DV-)PChlide-a and (DV-)PChlide-a'. The chiral-phase HPLC method enables the evaluation of the optical purity of (DV-)PChlide-a species. PChlide-a and/or DV-PChlide-a extracted from purple photosynthetic bacterial mutants were found to be mostly racemized, resulting in enantiomeric mixtures of (DV-)PChlides-a/a'.
BIOCHIMICA ET BIOPHYSICA ACTA-BIOENERGETICS
(2023)
Article
Chemistry, Multidisciplinary
Michael Kemper, Elric Engelage, Christian Merten
Summary: This study demonstrates the efficient transfer of point chirality in side chains of chiral triarylborane-ammonia adducts to the propeller chirality of triarylboranes. By using X-ray crystallography and spectroscopy, the conformational preferences of molecular propellers were elucidated. Interestingly, computationally predicted conformational preferences were found to be opposite to the experimentally observed ones.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Analytical
Vinayaka Harshothama Damle, Hagit Aviv, Yaakov R. Tischler
Summary: This study successfully identifies enantiomers using low-frequency Raman spectroscopy. By comparing the spectral intensity on different polarization planes, chiral and nonchiral molecules can be distinguished. This technique is of great importance for the pharmaceutical industry.
ANALYTICAL CHEMISTRY
(2022)
Article
Biochemistry & Molecular Biology
Venkateswara Rao Mundlapati, Zeynab Imani, Gildas Goldsztejn, Eric Gloaguen, Valerie Brenner, Katia Le Barbu-Debus, Anne Zehnacker-Rentien, Jean-Pierre Baltaze, Sylvie Robin, Michel Mons, David J. Aitken
Summary: The study investigated the conformational preferences of S-methyl-L-cysteine, showing that single Cys(Me) residues adopt a specific conformation in gas phase and low polarity solution, while consecutive Cys(Me) residues form a regular type I beta-turn structure without specific interactions. The comparison with a thietane amino acid highlighted the significance of side chain flexibility for the conformational behavior of Cys(Me).
Article
Chemistry, Physical
Jennifer Dupont, Valeria Lepere, Anne Zehnacker, Sebastian Hartweg, Gustavo A. Garcia, Laurent Nahon
Summary: Chirality and molecular conformation are crucial in molecular recognition, and valence-shell photoelectron circular dichroism (PECD) can sensitively detect them.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
Roberto Paciotti, Barbara Chiavarino, Cecilia Coletti, Debora Scuderi, Nazzareno Re, Davide Corinti, Lucretia Rotari, Simonetta Fornarini, Maria Elisa Crestoni
Summary: Genistein is a natural polyphenol belonging to the flavonoid family, known for its estrogenic properties and antioxidant, anti-inflammatory, and hormonal effects. Research has shown that its conjugate base exists as a specific isomeric form, involved in radical scavenging activity through proton transfer mechanisms.
Article
Chemistry, Physical
Jennifer Dupont, Regis Guillotb, Valeria Lepere, Anne Zehnacker
Summary: The structures of diastereomer diketopiperazine dipeptides cyclo(LTyr-LPhe) and cyclo-(DTyr-LPhe) were studied in the gas phase using resonance-enhanced two-photon ionization, IR/UV double resonance spectroscopy, and quantum chemical calculation. Both diastereomers exhibit two conformations with slight differences in weak CH···ir and NH···ir interactions. The crystal structure and vibrational circular dichroism spectrum were determined, with quantum chemical calculation shedding light on structural modifications between the gas phase and the solid state.
JOURNAL OF MOLECULAR STRUCTURE
(2022)
Article
Chemistry, Physical
Koki Yoshizawa, Keisuke Hirata, Shun-Ichi Ishiuchi, Masaaki Fujii, Anne Zehnacker
Summary: This study investigates the two diastereomers of the protonated diketopiperazine (DKP) dipeptide cyclo(Tyr-Tyr) using IR photodissociation spectroscopy and quantum chemical calculations. It is found that these diastereomers have similar structures with one folded ring over the DKP ring and the other extended in a trans geometry, forming a strong OH···π interaction. The neutral cyclo(LTyr-LTyr) dipeptide only exhibits a stacked geometry under supersonic expansion conditions, which is not observed in cyclo(LTyr-DTyr). In the protonated form, the strength of the OH···π interaction differs between the two diastereomers, resulting in significant differences in the nu(OH+) and protonated amide nu(NH) frequencies.
JOURNAL OF PHYSICAL CHEMISTRY A
(2022)
Article
Chemistry, Multidisciplinary
Sascha Jahnigen, Katia Le Barbu-Debus, Regis Guillot, Rodolphe Vuilleumier, Anne Zehnacker
Summary: In this study, the effect of a twofold screw axis on the solid-state VCD spectrum was investigated using both experimental and theoretical analysis. It was found that the VCD spectrum can reflect the supramolecular chirality of the crystal.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Chemistry, Multidisciplinary
Zeynab Imani, Venkateswara Rao Mundlapati, Valerie Brenner, Eric Gloaguen, Katia Le Barbu-Debus, Anne Zehnacker-Rentien, Sylvie Robin, David J. Aitken, Michel Mons
Summary: The delta conformation, a local secondary structure in proteins, is stabilized by specific side-chain/backbone N-H interactions in derivatives of a cyclic amino acid with a sulphur atom in the gamma-position. This allows the delta conformation to compete with classical C5 and C7 hydrogen bonded conformers, expanding the range of small-molecule models beyond rigid proline-type compounds.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Yining Jiang, Suvasthika Indrajith, Ariel Francis Perez Mellor, Thomas Buergi, Marc Lecouvey, Carine Clavaguera, Enrico Bodo, Chantal Houee-Levin, Estelle Loire, Giel Berden, Jos Oomens, Debora Scuderi
Summary: Reactive oxygen species (ROS) have specific functions in biological processes, but their uncontrolled production and reactivity can lead to pathophysiology. Methionine residues act as endogenous antioxidants, but the effect of oxidation on their structure is not well understood.
JOURNAL OF PHYSICAL CHEMISTRY B
(2022)
Article
Chemistry, Physical
Koki Yoshizawa, Keisuke Hirata, Shun-ichi Ishiuchi, Masaaki Fujii, Anne Zehnacker
Summary: The structure of alkali metal complexes of cyclic dipeptide cyclo Tyr-Tyr was determined by IRPD and quantum chemical calculations. The structure of the complexes depends on the chirality of the tyrosine residues. For residues of identical chirality, the metal cation interacts with one amide oxygen and one aromatic ring, while for residues of opposite chirality, the metal cation interacts with both aromatic rings. The distance between the aromatic rings is influenced by the metal. UV photodissociation spectroscopy and analysis of the UV photo-fragments revealed the excited state deactivation processes, which are influenced by the chirality of the residues and the metal ion core. Na+ shows low-lying charge transfer states, leading to broadening of the electronic spectrum.
Article
Multidisciplinary Sciences
Etienne Rouquet, Madhusree Roy Chowdhury, Gustavo A. Garcia, Laurent Nahon, Jennifer Dupont, Valeria Lepere, Katia Le Barbu-Debus, Anne Zehnacker
Summary: An achiral chromophore can exhibit a chiral spectroscopic signature in the presence of a chiral environment. In this study, the asymmetric scattering of a photoelectron ejected from an achiral chromophore interacting with a chiral host was observed, indicating the induction of a chiroptical response within the electric dipole approximation. This induced chirality has important implications in structural and analytical studies, particularly in the field of laser-based PECD.
NATURE COMMUNICATIONS
(2023)
Article
Chemistry, Physical
Taija L. Fischer, Margarethe Boedecker, Sophie M. Schweer, Jennifer Dupont, Valeria Lepere, Anne Zehnacker-Rentien, Martin A. Suhm, Benjamin Schroeder, Tobias Henkes, Diego M. Andrada, Roman M. Balabin, Haobam K. Singh, Himangshu P. Bhattacharyya, Manabendra Sarma, Silvan Kaser, Kai Topfer, Luis I. Vazquez-Salazar, Eric D. Boittier, Markus Meuwly, Giacomo Mandelli, Cecilia Lanzi, Riccardo Conte, Michele Ceotto, Fabian Dietrich, Vicente Cisternas, Ramachandran Gnanasekaran, Michael Hippler, Mahmoud Jarraya, Majdi Hochlaf, Narasimhan Viswanathan, Thomas Nevolianis, Gabriel Rath, Wassja A. Kopp, Kai Leonhard, Ricardo A. Mata
Summary: Vibrational spectroscopy in supersonic jet expansions is a powerful tool for benchmarking quantum chemical approaches. It provides potential benchmarking data for the critical analysis of procedures and unbiased testing opportunities. The results of the HyDRA blind challenge show promising predictive properties in both quantum mechanical approaches and machine learning strategies.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Arman Nejad, Ariel F. Perez Mellor, Manuel Lange, Ivan Alata, Anne Zehnacker, Martin A. Suhm
Summary: The hydrogen-bonded complexes formed between 2-naphthol (or beta-naphthol) and anisole were investigated using IR and UV absorption techniques. The experiments detected consistent hydrogen bonding between the OH group of 2-naphthol and the oxygen atom of anisole in different supersonic jet expansions. However, alternative hydrogen bonding to the aromatic ring of anisole was difficult to observe. The study highlights the importance of including three-body dispersion correction in theoretical calculations and suggests further investigations into related compounds.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2023)
Article
Chemistry, Physical
Katia Le Barbu-Debus, Ariel Perez-Mellor, Valeria Lepere, Anne Zehnacker
Summary: The protonated dimers of diketopiperazine dipeptides were examined to investigate the influence of stereochemistry on their clustering propensity. The results showed that the chirality of the residue has a significant impact on the formation of beta sheet patterns observed in amyloid type aggregation.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Physical
Taija L. Fischer, Margarethe Boedecker, Anne Zehnacker-Rentien, Ricardo A. Mata, Martin A. Suhm
Summary: The procedure for the first HyDRA blind challenge for predicting water donor stretching vibrations in monohydrates of organic molecules is described. A training set of 10 monohydrates with known experimental data is presented, along with a test set of 10 monohydrates with unknown water donor vibrational wavenumbers. The rules for data submissions from computational chemistry groups are outlined, and the planned publication procedure after the challenge is discussed.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
