A5011861467- Glycosylation and Glycoproteins Research
- Carbohydrate Chemistry and Synthesis
- Mass Spectrometry Techniques and Applications
- Chemical Synthesis and Analysis
- Analytical Chemistry and Chromatography
- Spectroscopy and Quantum Chemical Studies
- Protein Structure and Dynamics
- Crystallography and molecular interactions
- Advanced Chemical Physics Studies
- Enzyme Structure and Function
- Influenza Virus Research Studies
- Photochemistry and Electron Transfer Studies
- Legume Nitrogen Fixing Symbiosis
- Force Microscopy Techniques and Applications
- Various Chemistry Research Topics
- Computational Drug Discovery Methods
- Molecular spectroscopy and chirality
- Spectroscopy and Laser Applications
- Antimicrobial Peptides and Activities
- Polysaccharides and Plant Cell Walls
- Nonlinear Optical Materials Research
- Biopolymer Synthesis and Applications
- Organophosphorus compounds synthesis
- High-pressure geophysics and materials
- Neuropeptides and Animal Physiology
Hunter College
2011-2025
City University of New York
2011-2025
The Graduate Center, CUNY
2018-2025
CUNY Advanced Science Research Center
2021-2022
Fritz Haber Institute of the Max Planck Society
2015-2019
Challenges in quantifying how force affects bond formation have hindered the widespread adoption of mechanochemistry. We used parallel tip-based methods to determine reaction rates, activation energies, and volumes force-accelerated [4+2] Diels-Alder cycloadditions between surface-immobilized anthracene four dienophiles that differ electronic steric demand. The rate dependences on pressure were unexpectedly strong, substantial differences observed dienophiles. Multiscale modeling...
The diversity of stereochemical isomers present in glycans and glycoconjugates poses a formidable challenge for comprehensive structural analysis. Typically, sophisticated mass spectrometry (MS)-based techniques are used combination with chromatography or ion-mobility separation. However, coexisting structurally similar often render an unambiguous identification impossible. Other powerful such as gas-phase infrared (IR) spectroscopy have been limited to smaller glycans, since conformational...
A big hurdle when entering the field of carbohydrate research stems from complications in analytical and computational treatment. In effect, this extremely important class biomolecules remains underinvestigated compared, for example, with maturity genomics proteomics research. On theory side, commonly used empirical methods suffer an insufficient amount high-quality experimental data against which they can be thoroughly validated. order to provide a pivotal point ascent accurate simulations,...
The stereoselective formation of 1,2-cis-glycosidic bonds is challenging. However, 1,2-cis-selectivity can be induced by remote participation C4 or C6 ester groups. Reactions involving are believed to proceed via a key ionic intermediate, the glycosyl cation. Although mechanistic pathways were postulated many years ago, structure reaction intermediates remained elusive owing their short-lived nature. Herein, we unravel cations involved in reactions cryogenic vibrational spectroscopy and...
Abstract Glycolipids are complex glycoconjugates composed of a glycan headgroup and lipid moiety. Their modular biosynthesis creates vast amount diverse often isomeric structures, which fulfill highly specific biological functions. To date, no gold-standard analytical technique can provide comprehensive structural elucidation glycolipids, insufficient tools for isomer distinction lead to wrong assignments. Herein we use cryogenic gas-phase infrared spectroscopy systematically investigate...
Mechanical activation of reactions can reduce significantly the amounts solvent and energy required to form covalent organic bonds.
Abstract Glycosyl cations are the key intermediates during glycosylation reaction that covalently links building blocks synthetic assembly of carbohydrates. The exact structure these ions remained elusive due to their transient and short-lived nature. Structural insights into intermediate would improve our understanding mechanism glycosidic bond formation. Here, we report an in-depth structural analysis glycosyl using a combination cold-ion infrared spectroscopy first-principles theory....
The amino acid serine has long been known to form a protonated "magic-number" cluster containing eight monomer units that shows an unusually high abundance in mass spectra and remarkable homochiral preference. Despite many experimental theoretical studies, there is no consensus on Ser8H+ structure agreement with all observations. Here, we present the of determined by combination infrared spectroscopy ab initio molecular dynamics simulations. three-dimensional determine ∼25 kcal mol–1 more...
Fucose is an essential deoxysugar that found in a wide range of biologically relevant glycans and glycoconjugates. A recurring problem mass spectrometric analyses fucosylated the intramolecular migration fucose units, which can lead to erroneous sequence assignments. This reaction typically assigned activation during collision-induced dissociation (CID) tandem spectrometry (MS). In this work, we utilized cold-ion spectroscopy show for first time not limited fragments obtained MS also be...
Ion-mobility mass spectrometry and DFT calculations reveal the surprisingly solvent-dependent formation of large pentameric [N⋯I<sup>+</sup>⋯N] halogen-bonded capsules.
Fucose is a signaling carbohydrate that attached at the end of glycan processing. It involved in range processes, such as selectin-dependent leukocyte adhesion or pathogen-receptor interactions. Mass-spectrometric techniques, which are commonly used to determine structure glycans, frequently show fucose-containing chimeric fragments obfuscate analysis. The rearrangement leading these fragments-often referred fucose migration-has been known for more than 25 years, but chemical identity...
We compare dispersion and induction interactions for noble gas dimers Ne, methane, 2-butyne with HF LiF using a variety of functionals (including some specifically parameterized to evaluate interactions) ab initio methods including CCSD(T) MP2. see that inductive tend enhance may be accompanied by charge-transfer. show the do not generally follow expected trends in interaction energies, basis set superposition errors (BSSE), distances as function size. The treat often overestimate these...
Fucose migration reactions represent a substantial challenge in the analysis of fucosylated glycan structures by mass spectrometry. In addition to well-established observation transposed fucose residues glycan-dissociation product ions, recent experiments show that rearrangement can also occur intact ions. These results suggest low-energy barrier for residue and broaden relevance include other types spectrometry experiments, including ion mobility-mass spectroscopy. this work, we utilize...
Using methods of DFT, we investigated the effect electron withdrawing and donating groups on relative stability tentative glycosyl donor reaction intermediates. The calculation shows that by changing stereoelectronic properties protecting group, can influence dioxolenium type intermediates up to 10 kcal mol−1, increasing nucleophillicity 4-O-Bz intermediate becomes more stable than a triflate–donor pair. We exploited this mechanism design galactosyl donors with custom O2 O4, outcome...
The proton-bound dicarboxylate motif, RCOO- ⋅H+ ⋅- OOCR, is a prevalent chemical configuration found in many condensed-phase systems. formate dimer HCOO- OOCH was studied utilizing cold-ion IR action spectroscopy the range 400-1800 cm-1 . spectrum obtained at ca. 0.4 K of ions captured He nanodroplets compared to that measured 10 by photodissociation Ar-ion complexes. Similar band patterns are two techniques consistent with calculations for C2 symmetry structure proton shared equally between...
Synthetic carbohydrate receptors could serve as agents for disease detection, drug delivery, or even therapeutics, however, they are rarely used these applications because bind weakly and with a preference towards the all-equatorial glucosides that not prevalent on cell surface. Herein binding of 8 5 distinct octyloxy pyranosides, which was measured by mass spectrometry 1 H NMR titrations in CD2 Cl2 at 298 K, is reported, providing affinities vary from ≈101 -104 m-1 . Although promiscuous,...
Polyoxometalate clusters possess unique catalytic and electromagnetic properties. The structure function of polyoxometalates is dictated by complex oligomerization processes, which in turn depend on the solution conditions. In this work, small gas-phase polyoxomolybdate nanoclusters (HMonO3n+11–, n = 1–8, MonO3n+12–, 2–8) were investigated after nanoelectrospray an acidified ammonium heptamolybdate heptahydrate ion mobility spectrometry–mass spectrometry (IMS–MS), infrared multiple photon...
Carbohydrate–receptor interactions are often involved in the docking of viruses to host cells, and this is a necessary step virus life cycle that precedes infection and, ultimately, replication. Despite conserved structures glycans docking, they still considered "undruggable", meaning these beyond scope conventional pharmacological strategies. Recent advances development synthetic carbohydrate receptors (SCRs), small molecules bind carbohydrates, could bring carbohydrate–receptor within...
Peptides have tremendous potential as building blocks of designer materials with wide-ranging applications. These are stabilized by strongly directional hydrogen bonding patterns giving rise to one-, or two-dimensional assembly. It remains a challenge mimic biology’s context-adaptive and flexible structures. Here, we introduce minimalistic tripeptide sequences that form dynamic ensembles through incorporation multivalent sidechain interactions collectively self-optimize depending on their...
We present density functional theory (DFT) calculations at the X3LYP/D95(d,p) level on solvation of polyalanine α-helices in water. The study includes effects discrete water molecules and CPCM AMSOL SM5.2 solvent continuum model both separately combination. find that individual cooperatively hydrogen-bond to C- N-termini helix, which results increases dipole moment helix/water complex more than vector sum their moments. These waters are found be stable bulk solvent. On other hand, interact...
We compare the energetic and structural properties of fully optimized α-helical antiparallel β-sheet polyalanines differences between axial equatorial conformations three cyclohexane derivatives (methyl, fluoro, chloro) as calculated using several functionals designed to treat dispersion (B97-D, ωB97x-D, M06, M06L, M06-2X) with other traditional not specifically parametrized (B3LYP, X3LYP, PBE1PBE) experimental results. Those developed significantly overestimate interaction enthalpies...
Abstract Die stereoselektive Bildung von 1,2‐ cis ‐glykosidischen Bindungen ist bislang sehr anspruchsvoll. Häufig wird diese ‐Selektivität durch Fernpartizipation (remote participation) C4‐ oder C6‐Estergruppen herbeigeführt. Hierbei davon ausgegangen, dass ein ionisches Schlüsselintermediat, das Glykosylkation, gebildet wird. Obwohl derartige Mechanismen bereits vor Jahrzehnten postuliert wurden, konnte die exakte Struktur dieses Intermediats aufgrund seiner Kurzlebigkeit bisher nicht...
Polyalanine based peptides that carry a lysine at the C-terminus ([Ac-AlanLys + H](+)) are known to form α-helices in gas phase. Three factors contribute stability of these helices: (i) interaction between helix macro dipole and charge, (ii) capping dangling C[double bond, length as m-dash]O groups by (iii) cooperative hydrogen bond network. In previous studies, influence charge well impact was studied intensively. Here, we complement findings systematically assessing third parameter, H-bond...
Synthetic carbohydrate receptors (SCRs) that selectively recognize cell-surface glycans could be used for detection, drug delivery, or as therapeutics. Here we report the synthesis of seven new C2h symmetric tetrapodal SCRs. The structures these SCRs possess a conserved biaryl core, and they vary in four heterocyclic binding groups are linked to core via secondary amines. Supramolecular association between five biologically relevant C1 -O-octyloxy glycans, α/β-glucoside (α/β-Glc),...