A5035425997- Mass Spectrometry Techniques and Applications
- Analytical Chemistry and Chromatography
- Radical Photochemical Reactions
- Advanced Chemical Physics Studies
- Free Radicals and Antioxidants
- Molecular Sensors and Ion Detection
- Neurotransmitter Receptor Influence on Behavior
- Chemical Synthesis and Analysis
- Behavioral Health and Interventions
- Chemical Reaction Mechanisms
- Electron Spin Resonance Studies
- Metal complexes synthesis and properties
- Advanced Proteomics Techniques and Applications
- Spectroscopy and Quantum Chemical Studies
- Hemoglobin structure and function
- Neuroendocrine regulation and behavior
- Decision-Making and Behavioral Economics
- Ferrocene Chemistry and Applications
- Substance Abuse Treatment and Outcomes
- Analytical chemistry methods development
- Electrochemical Analysis and Applications
- Photoreceptor and optogenetics research
- DNA and Nucleic Acid Chemistry
- Redox biology and oxidative stress
- Protein Structure and Dynamics
Hong Kong Polytechnic University
2003-2025
York University
2013-2024
University of Windsor
2014-2024
University of California, San Diego
2021-2024
Hong Kong Baptist University
2010-2023
Stony Brook University
2022
Scripps Research Institute
2021
Toronto Public Health
2015-2020
Resonance Research (United States)
2018
Mayo Clinic
2018
All three hydrolysis reactions of the anticancer drug cisplatin, cis-[Pt(NH3)2Cl2], including acidity constants (pKa) aqua complexes have been compared using a combined density functional theory (DFT) and continuum dielectric model (CDM) approach. The calculations predict very similar activation barriers (25-27 kcal/mol) reaction free energies (0-2 for each reactions. predicted relative both Pt(II) Ru(II) agree well with available experimental values. However, our calculated data strongly...
A comparative quantum chemical approach helps to clarify how the selectivity of anticancer metallopharmaceuticals towards potential biological targets can be controlled by metal and ligands.
Potential consequences of the binding anticancer drug cisplatin to various biomolecules in cell have been investigated by using a combined density functional theory and continuum dielectric model approach. Since amine ligands remain coordinated at metal upon formation most frequent DNA adducts, whereas they were found be displaced from metabolites, we analyzed factors governing loss platinum(II) complexes as possible pathway inactivation. The calculations systematically show effect 1) trans...
Cisplatin, or cis-[Pt(NH3)2Cl2], was the first member of a new revolutionary class anticancer drugs that is still used today for treatment wide variety cancers. The mode action cisplatin starts inside cell with hydrolysis Pt–Cl bonds to form Pt–aqua complex. solvent environment plays an essential role in many biochemical processes general, and expected have particular strong effect on activation (hydrolysis) derivatives. To investigate these effects, we studied explicit structures during by...
Gas-phase complexes of five metal ions with the dipeptide HisGly have been characterized by DFT computations and infrared multiple photon dissociation spectroscopy (IRMPD) using free electron laser FELIX. Fine agreement is found in all cases between predicted IR spectral features lowest energy structures observed IRMPD spectra diagnostic region 1500-1800 cm(-1), largely satisfactory at longer wavelengths from 1000 to 1500 cm(-1). Weak-binding (K(+), Ba(2+), Ca(2+)) predominantly adopt...
Addiction is commonly characterized by escalation of drug intake, compulsive seeking, and continued use despite harmful consequences. However, the factors contributing to transition from moderate these problematic patterns remain unclear, particularly regarding role sex. Many preclinical studies have been limited small sample sizes, low genetic diversity, restricted access, making it challenging model significant levels intoxication or dependence translate findings humans. To address...
The potassium cation affinities (PCAs) of 136 ligands (20 classes) in the gas phase were established by hybrid density functional theory calculations (B3-LYP with 6-311+G(3df,2p) basis set). For these ligands, 70 experimental values are available for comparison. Except five specific PCA values-those phenylalanine, cytosine, guanine, adenine (kinetic-method measurement), and Me(2)SO (by high-pressure mass spectrometric equilibrium measurement)-our theoretical estimates excellent agreement...
In this work, we regiospecifically generate and compare the gas-phase properties of two isomeric forms tryptophan radical cations—a distonic indolyl N-radical (H3N+ - TrpN•) a canonical aromatic π (Trp•+) cation. The cation was generated by nitrosylating indole nitrogen in solution followed collision-induced dissociation (CID) resulting protonated N-nitroso tryptophan. π-radical produced via CID ternary [CuII(terpy)(Trp)] •2+ complex. spectra species were found to be very different,...
Background: Parkinson's disease (PD) is a neurodegenerative in which the progressive loss of dopaminergic neurons (DA) leads to initially sporadic and eventually widespread damage nervous system resulting significant musculoskeletal cognitive deterioration. Loss motor function alongside increasing impairment part natural progression. Gait often considered an automatic activity; however, walking result delicate balance multiple systems maintain body's center mass over ever-changing base...
Infrared multiple-photon dissociation (IRMPD) spectroscopy and DFT calculations have been used to probe the most stable structures of a3(*) a4(*) ions derived from both protonated pentaglycine (denoted G5) pentaalanine (A5). The A5 feature a CHR=N-CHR'- group at N-terminus an oxazolone ring C-terminus, as proposed previously [J. Am. Soc. Mass Spectrom. 19, 1788-1798 (2008)]. isomeric ion with 3,5-dihydro-4H-imidazol-4-one structure was calculated slightly better energy than oxazolone, but...
Collision-induced charge disproportionation limits the stability of triply charged metal ion complexes and has thus far prevented successful acquisition their gas-phase IR spectra. This curtailed our understanding structures in gas phase biological environments. Herein we report first spectra LaIII with a derivative tryptophan (N-acetyl methyl ester), an unusual dissociation product, lanthanum amidate. These are compared those predicted using density functional theory. The best lowest...
Peptide radical cations A(n)Y(•+) (where n = 3, 4, or 5) and A5W(•+) have been generated by collision-induced dissociation (CID) of [Cu(II)(tpy)(peptide)](•2+) complexes. Apart from the charge-driven fragmentation at N-Cα bond hetero residue producing either [c + 2H](+) [z - H](•+) ions radical-driven Cα-C to give a(+) ions, unusual product [x are abundant in CID spectra peptides with second third position chain. The formation these requires that both charge be located on peptide backbone....
Intramolecular hydrogen atom transfer (HAT) was examined in homocysteine (Hcy) thiyl radical/alkali metal ion complexes the gas phase by combination of experimental techniques (ion-molecule reactions and infrared multiple photon dissociation spectroscopy) theoretical calculations. The results unequivocally show that complexation (as opposed to protonation) regiospecifically generated Hcy radical promotes its rapid isomerisation into an α-carbon via HAT. Theoretical calculations were employed...
The formation and investigation of sulfur-based cysteine radicals cationized by a group 1A metal ion or Ag+ in the gas phase are reported. Gas-phase ion-molecule reactions (IMR) infrared multiple-photon dissociation (IRMPD) spectroscopy revealed that Li+ , Na+ K+ adducts radical remain S-based as initially formed. Theoretical calculations for three alkali ions found lowest-energy isomers Cα -based radicals, but they not observed experimentally owing to barriers associated with hydrogen-atom...
This work describes investigation of the fragmentation mechanism tryptophan N-indolyl radical cation, H3N(+)-TrpN(•) (m/z 204) studied via DFT calculations and several gas-phase experimental techniques. The main fragment ion at m/z 131, shown to be a mixture up four isomers including 3-methylindole (3MI) π-radical was found undergo further loss an H atom yield one two isomeric 130 ions. 3-Methylindole cation generated independently (via CID [Cu(II)(terpy)3MI](•2+)) displayed reactivity...
Two types of radical cations tryptophan—the π-radical cation and the protonated tryptophan-N radical—have been studied in dipeptides AW WA. The produced by removal an electron during collision-induced dissociation a ternary Cu(II) complex was only observed for peptide. In case WA, ion corresponding to loss ammonia, [WA–NH 3 ] •+ , from copper complex. Both radicals were N-nitrosylation neutral peptides followed transfer gas phase via electrospray ionization subsequent dissociation....
Radical cations [Met-Gly](•+), [Gly-Met](•+), and [Met-Met](•+) have been generated through collision-induced dissociation (CID) of [Cu(II)(CH3CN)2(peptide)](•2+) complexes. Their fragmentation patterns mechanisms studied both experimentally theoretically using density functional theory at the UB3LYP/6-311++G(d,p) level. The captodative structure, in which radical is located α-carbon N-terminal residue proton on amide oxygen, lowest energy structure each potential surface. canonical with...