Article
Chemistry, Physical
Kris Strunge, Tucker Burgin, Thaddeus W. Golbek, Steven J. Roeters, Jim Pfaendtner, Tobias Weidner
Summary: α-synuclein folds into a defined secondary structure at the air-water interface, promoting its aggregation and fibrillation. Understanding the role of hydrophobic surfaces in this process is important for studying severe brain disorders such as Parkinson's disease.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2023)
Article
Biochemistry & Molecular Biology
Giulia Giubertoni, Federico Caporaletti, Steven J. Roeters, Adam S. Chatterley, Tobias Weidner, Peter Laity, Chris Holland, Sander Woutersen
Summary: The mechanical properties of biomaterials are influenced by the interactions and conformations of their protein building blocks. Infrared spectroscopy is a commonly used method for studying molecular structures, and polarized two-dimensional infrared spectroscopy (2D-IR) is applied in this study to identify the protein secondary structures in native silk films. The results show changes in the secondary structure due to hydration, with an increase in random coil content and a decrease in helical content.
Article
Biochemistry & Molecular Biology
Ali Moazzam, Vesna Stanojlovic, Arthur Hinterholzer, Christoph Holzner, Cornelia Roschger, Andreas Zierer, Markus Wiederstein, Mario Schubert, Chiara Cabrele
Summary: Side-chain-to-side-chain cyclization is a common method to stabilize the alpha-helical conformation of short peptides. This study investigates the effects of incorporating a lactam bridge in a nonapeptide and shows that while the cyclized segment adopts a helical turn, deviations from ideal helix geometry occur. It also explores the impact of different hydrophobic residues on the helical structure.
JOURNAL OF PEPTIDE SCIENCE
(2022)
Review
Biochemistry & Molecular Biology
Martin B. Smith
Summary: Organophosphorus ligands play crucial roles in coordination chemistry and catalysis, thanks to their easily tunable properties. Diphosphines, compounds with two separated P-III donor atoms, are highly valued for their excellent chelating properties upon complexation with metals. Incorporating nitrogen-based groups into ligands can lead to unusual reactivities and important catalytic applications.
Article
Chemistry, Physical
Satish Kumar, Kshetrimayum Borish, Sanjit Dey, Jayashree Nagesh, Aloke Das
Summary: The folding motifs of Gly-Pro and Pro-Gly dipeptides were investigated and their structures were found to be dependent on the hydrogen bonding interactions. The structure of Gly-Pro peptide was consistent between gas phase and solution phase, while the Pro-Gly peptide had different structures in gas phase and solution phase. Solvent might play a crucial role in dictating the preferential stabilization of the C10 structure in the solution phase.
PHYSICAL CHEMISTRY CHEMICAL PHYSICS
(2022)
Article
Chemistry, Applied
Xiaoshuang Yan, Biaolan Liu, Geying Ru, Jiwen Feng
Summary: This study elucidates the conformation of single-helical curdlan generated in specific conditions and its different interactions with Congo Red compared to random-coil curdlan, offering insights into the specific structure-activity relationship of beta-(1,3)-glucans.
CARBOHYDRATE POLYMERS
(2021)
Article
Chemistry, Physical
Kai Xue, Evgeny Nimerovsky, Kumar A. Tekwani Movellan, Stefan Becker, Loren B. Andreas
Summary: A new proton-detection method has been developed to measure protein torsion angles by recoupling NH and CH dipolar couplings, applicable to protonated or partly deuterated samples. The efficiency and precision of the method were demonstrated with microcrystalline chicken α-spectrin SH3 protein and the influenza A matrix 2 (M2) membrane protein. Pseudo-4D data for M2 revealed a turn between transmembrane and amphipathic helices.
JOURNAL OF PHYSICAL CHEMISTRY LETTERS
(2022)
Article
Chemistry, Multidisciplinary
In Gyu Bak, Chang-Guen Chae, Jieun Choi, Woo-Young Song, Jiwon Seo, Eunji Lee, Jae-Suk Lee
Summary: The amphiphilic conformation of alpha-helical peptides, with important biological functions, can be mimicked by alternating polyisocyanate copolymers. The benzyl group of SMBIC and the alkene group of AIC play crucial roles in the alternating copolymerization process, resulting in copolymers with controlled molecular weight and narrow dispersity. N-P(AIC-alt-SMBIC)s were synthesized from thiol-ene radical addition with P(AIC-alt-SMBIC).
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Bruno Linclau, Zhong Wang, Benjamin Jeffries, Jerome Graton, Rodrigo J. Carbajo, Davy Sinnaeve, Jean-Yves Le Questel, James S. Scott, Elisabetta Chiarparin
Summary: Efficient drug discovery relies on optimizing bioactivity and compound properties such as lipophilicity, guided by efficiency metrics; the use of conformer-specific lipophilicities is a less explored strategy; optimizing lipophilicity values for different conformers can create a novel avenue in drug discovery.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2022)
Article
Chemistry, Multidisciplinary
Sinead McCann, William E. Roe, Hannah E. Agnew, Peter C. Knipe
Summary: To imitate the dynamic molecules in biological systems, foldamers need to possess stimulus-responsive behavior. In this study, we present a foldamer architecture based on alternating pyridine-diketopiperazine linkers. Epimerization is prevented via a copper-catalyzed coupling protocol. The native conformation of the compounds is initially investigated in both solid and solution states. The foldamers can be solubilized in DMSO and pH 9.5 buffer while retaining conformational control. Furthermore, dynamic switching is demonstrated through acid treatment, resulting in stimulus-responsive sidechain reconfiguration.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2023)
Article
Biochemistry & Molecular Biology
Yoshihiro Nishida, Reina Aono, Hirofumi Dohi, Wuxiao Ding, Hirotaka Uzawa
Summary: Glycerol exhibits symmetrical conformations with different ratios of gt, gg, and tg in water, favoring the symmetric conformers with the 1,2,3-triol groups in gauche/gauche geometry. However, the conformational equilibrium of glycerol shifts towards non-symmetric conformers when the solvent is changed to DMSO-d(6) or DMF-d(7).
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2023)
Review
Chemistry, Multidisciplinary
Peng Sang, Jianfeng Cai
Summary: Unnatural helical peptidic foldamers are attracting attention due to their unique folding behaviors, diverse protein binding mechanisms, and promising applications in various fields. They are comprised of well-defined backbone conformers with unusual structural parameters and can exhibit intriguing three-dimensional helical structures. These foldamers have superior resistance to degradation, enhanced bioavailability, and improved chemodiversity, making them potential mimics of protein helical segments.
CHEMICAL SOCIETY REVIEWS
(2023)
Review
Biochemistry & Molecular Biology
Deborah E. Shalev
Summary: Metal chelation plays an important role in providing structural stability and forming reactive centers in metalloproteins. Peptide-metal complexes, which exist in nature, offer a way to study protein binding regions and control experimental variables effectively.
INTERNATIONAL JOURNAL OF MOLECULAR SCIENCES
(2022)
Article
Biochemistry & Molecular Biology
Lucia De Rosa, Donatella Diana, Rossella Di Stasi, Alessandra Romanelli, Michele F. M. Sciacca, Danilo Milardi, Carla Isernia, Roberto Fattorusso, Luca D. D'Andrea
Summary: Replacing leucine 10 in the QK peptide with different hydrophobic amino acids leads to changes in helical content and thermal stability, depending on the type of interaction that could be established between Leu7 and the residue in position 10. Interestingly, the changes in helical content and thermal stability are not always correlated, highlighting the complex nature of these interactions.
BIOORGANIC CHEMISTRY
(2021)
Article
Polymer Science
Timo Imhof, Jonas Kind, Christina M. Thiele
Summary: We studied the temperature-dependent LLC behavior of helically chiral polypeptides, specifically PBPMLG and PBLA-co-PPLA. We observed a characteristic jump in the quadrupolar splittings Delta nu Q of the solvent's 2H signal during the transition of polymer rods from perpendicular to parallel orientation with respect to the magnetic field. By correlating Delta nu Q with the diffusion coefficients measured parallelly (D parallel to) and perpendicularly (D perpendicular to) to the magnetic field, we found a significant change in the D parallel to/D perpendicular to ratio at the transition temperature of the LLC phases.
Article
Chemistry, Multidisciplinary
Prathama S. Mainkar, Ambica Vankamamidi, Srivari Chandrasekhar
Summary: In the past, twinning in research publications was serendipitous, but it has become more frequent nowadays. This may be attributed to researchers' desire to publish on popular topics, base research programs on popular keywords, and funding agencies preferentially supporting certain areas of research.
ANGEWANDTE CHEMIE-INTERNATIONAL EDITION
(2021)
Article
Chemistry, Organic
Md Nirshad Alam, Soumya Ranjan Dash, Anirban Mukherjee, Satish Pandole, Udaya Kiran Marelli, Kumar Vanka, Pradip Maity
Summary: The thermal O-to-C [1,3]-rearrangement of alpha-hydroxy acid derived enol ethers was achieved under mild conditions, facilitated by the 2-aminothiophenol protection of carboxylic acids. Experimental and theoretical evidence was presented for dissociative radical pair formation, captodative stability via aminothiophenol, and a unique solvent effect. Aminothiophenol was deprotected from rearrangement products and after derivatization to useful synthons.
Article
Chemistry, Organic
Kishore Kumar Palli, Raghunath Reddy Anugu, Srivari Chandrasekhar
Summary: The synthesis of (-)-4-epi-Englerin A, the epimer of natural product (-)-Englerin A, is achieved from (R)-(+)-limonene, utilizing Sharpless asymmetric dihydroxylation, aldol reaction, and transannular epoxide opening reactions. These key features install the required functionalities of oxabridged tricyclic core in the compound with exceptional anti-proliferative activity in renal cancer cells.
EUROPEAN JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Telugu Venkatesh, Prathama S. Mainkar, Srivari Chandrasekhar
Summary: The formal synthesis of (+/-)-cochlearol A was achieved using Suzuki coupling and Friedel-Crafts cyclization as a convergent strategy to functionalize the tetralone ring, and an intramolecular construction of the C/D ring involving sequential epoxide formation/acetal formation.
JOURNAL OF ORGANIC CHEMISTRY
(2021)
Article
Chemistry, Organic
Karekar Sanjeev, Silver Raju, Srivari Chandrasekhar
Summary: Efficient synthesis of cycloalkyl-fused naphthalenes was achieved through [4 + 2]-cycloaddition/decarboxylative aromatization of alkyne-tethered aryne insertion adducts, which are difficult to synthesize using conventional methods. The reaction proceeds via benzopyrylium intermediate formation, intramolecular [4 + 2] cycloaddition, and subsequent decarboxylation pathway. Compatibility with allene-tethered substrates and one-pot synthesis of polysubstituted naphthalenes via aryne insertion/benzannulation were also demonstrated.
Article
Chemistry, Multidisciplinary
Nandikolla Krishna Chaitanya, Y. N. Sambasiva Rao, Venkata Surya Kumar Choutipalli, Prathama S. Mainkar, Venkatesan Subramanian, Srivari Chandrasekhar
Summary: Cyclic and acyclic vinyl-substituted β-keto/enol carbonyl substrates react with arynes to yield differentially substituted naphthyl carbocycles. The ring size of the cyclic β-keto/enol esters plays a significant role in product formation.
CHEMICAL COMMUNICATIONS
(2022)
Article
Chemistry, Organic
Shweta Rai, Polasani Samatha, Ramunaidu Addipilli, Prathama S. Mainkar, Prabhakar Sripadi, Raju Adepu, Srivari Chandrasekhar
Summary: This study demonstrates the use of Poly(ethylene glycol) dimethyl ethers (PEGDMEs) as solvents for various aryne reactions without the need for any additives. The reactions proceed efficiently and the desired products can be obtained in good yields. Furthermore, the advantage of PEG solvent recycling is shown in this work.
SYNTHESIS-STUTTGART
(2022)
Article
Chemistry, Organic
Y. N. Sambasiva Rao, Palash Ghosh, Prathama S. Mainkar, Srivari Chandrasekhar
Summary: An efficient and metal-free strategy has been developed for the synthesis of spiro-fused indanolactones/lactams via the reaction of arynes with alpha-chloroacetyl lactones/lactams. This strategy allows for the access to spiroindanone derivatives through aryne insertion/spirocyclization.
Article
Chemistry, Multidisciplinary
Jadhav Rahul Dhanaji, Polasani Samatha, Silver Raju, Prathama S. Mainkar, Raju Adepu, Srivari Chandrasekhar
Summary: The aryne insertion reaction with 2-aroyl malonates/cyanoesters leads to the formation of diarylmethane or chromones, depending on the substitution on the aryne ring. Chromones are generated when an electronegative atom is present at the ortho position of arynes, while other arynes undergo a cascade double aryne insertion to form diarylmethanes.
CHEMICAL COMMUNICATIONS
(2023)
Article
Chemistry, Inorganic & Nuclear
Subhashree S. Kanungo, Abhaya Kumar Mishra, Nitin B. Mhamane, Udaya Kiran Marelli, Dharmesh Kumar, Chinnakonda S. Gopinath
Summary: This study demonstrates the preparation of metal-ion-doped ceria-zirconia solid solution using a sol-gel technique, and shows the influence of different metal-ion combinations on the selectivity of methane activation.
INORGANIC CHEMISTRY
(2022)
Article
Chemistry, Multidisciplinary
Silver Raju, Palash Ghosh, Kiranmai Nayani, Jupally Prashanth, Balasubramanian Sridhar, Prathama S. Mainkar, Srivari Chandrasekhar
Summary: Cascade aza-Piancatelli reaction and [3+3]/[4+2] cycloaddition reactions can generate octahydro-4H-cyclopenta[b]pyridin-6-one scaffolds. In addition, octahydro-5,7a-epoxycyclopenta[cd]isoindol-4-one frameworks of gracilamine alkaloid and a novel decahydro-1H-dicyclopenta[cd,hi]isoindol-6-one can also be synthesized with excellent regio- and diastereo-selectivities.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Multidisciplinary
Abha Dangi, Udaya Kiran Marelli
Summary: A total of 15 cyclic-hexaalanine and 10 cyclic-pentaalanine peptides containing one or two backbone N-aryl amide bonds were synthesized. NMR-based conformation studies revealed distinct template conformations with an antiparallel beta-sheet structure for cyclic-hexaalanine peptides, and three template structures for cyclic-pentaalanine peptides. The N-aryl peptides exhibited considerable conformational homogeneity and differed significantly from N-methyl analogues. The N-arylation of backbone amides has potential as a novel tool for conformational and physicochemical modification in peptides.
CHEMISTRY-A EUROPEAN JOURNAL
(2023)
Article
Chemistry, Organic
Abha Dangi, Bharat Pande, Sonia Agrawal, Dhiman Sarkar, Koteswara Rao Vamkudoth, Udaya Kiran Marelli
Summary: The first total synthesis of icosalide A, an antibacterial depsipeptide containing two lipophilic beta-hydroxy acids, was achieved using Fmoc solid-phase peptide synthesis and solution-phase synthesis. The absolute stereochemistry of icosalide A was determined by synthesizing reported structures and relevant diastereomers of icosalides and comparing their NMR data. Icosalide A exhibited a well-folded structure with cross-strand hydrogen bonds, and its analogues displayed antibacterial activity against Bacillus thuringiensis and Paenibacillus dendritiformis, as well as inhibitory effects on Mycobacterium tuberculosis and cancer cell lines HeLa and ThP1.
ORGANIC & BIOMOLECULAR CHEMISTRY
(2023)
Article
Chemistry, Organic
Kailas V. Preeti, Kailas V. Kallurkar, Prathama S. Mainkar, Raju Adepu, Srivari Chandrasekhar
Summary: A concise route for the synthesis of dihydrobenzo-[j]-phenanthridinones has been developed using an aryne annulation strategy under metal-free reaction conditions. The reaction involves multiple C-C and C-N bond cleavages/formations through Diels-Alder reaction, aromatization-driven C-N bond cleavage, and amide formation.
Article
Chemistry, Multidisciplinary
Pooja R. Solanke, Radhika Cinsani, Kiranmai Nayani, Prathama S. Mainkar, Srivari Chandrasekhar
Summary: A new and efficient approach to synthesizing multifunctionalized spirocyclopentenone scaffolds through Piancatelli rearrangement under metal-free conditions has been developed. This method has been successfully applied to O-, N-, and C-nucleophiles, yielding excellent results.
CHEMICAL COMMUNICATIONS
(2022)
