Browse
Submit Data
Databases
API
Help

Dataset Information

17 Views

0 Connections

0 Citations

0 Reanalyses

0 Downloads

Omics score: 0

Switching the Mechanism of NADH Photooxidation by Supramolecular Interactions.

ABSTRACT: A series of three Ru(II) polypyridine complexes was investigated for the selective photocatalytic oxidation of NAD(P)H to NAD(P)⁺ in water. A combination of (time-resolved) spectroscopic studies and photocatalysis experiments revealed that ligand design can be used to control the mechanism of the photooxidation: For prototypical Ru(II) complexes a ¹ O₂ pathway was found. Rudppz ([(tbbpy)₂ Ru(dppz)]Cl₂ , tbbpy=4,4'-di-tert-butyl-2,2'-bipyridine, dppz=dipyrido[3,2-a:2',3'-c]phenazine), instead, initiated the cofactor oxidation by electron transfer from NAD(P)H enabled by supramolecular binding between substrate and catalyst. Expulsion of the photoproduct NAD(P)⁺ from the supramolecular binding site in Rudppz allowed very efficient turnover. Therefore, Rudppz permits repetitive selective assembly and oxidative conversion of reduced naturally occurring nicotinamides by recognizing the redox state of the cofactor under formation of H₂ O₂ as additional product. This photocatalytic process can fuel discontinuous photobiocatalysis.

SUBMITTER: Mengele AK

PROVIDER: S-EPMC9298348 | biostudies-literature |

REPOSITORIES: biostudies-literature

ACCESS DATA

Json Xml

Similar Datasets

Phenothiazine Dyes Induce NADH Photooxidation through Electron Transfer: Kinetics and the Effect of Copper Ions.

Project description:Phenothiazine dyes, methylene blue, new methylene blue, azure A, and azure B, photosensitized the oxidation of nicotinamide adenine dinucleotide (NADH), an important coenzyme in the living cells, through electron transfer. The reduced forms of these phenothiazine dyes, which were produced through electron extraction from NADH, underwent reoxidation to the original cationic forms, leading to the construction of a photoredox cycle. This reoxidation process was the rate-determining step in the photoredox cycle. The electron extraction from NADH using phenothiazine dyes can trigger the chain reaction of the NADH oxidation. Copper ions enhanced the photoredox cycle through reoxidation of the reduced forms of phenothiazine dyes. New methylene blue demonstrated the highest photooxidative activity in this experiment due to the fast reoxidation process. Electron-transfer-mediated oxidation and the role of endogenous metal ions may be important elements in the photosterilization mechanism.

| S-EPMC8015084 | biostudies-literature

Wavelength dependent mechanism of phenolate photooxidation in aqueous solution.

Project description:Phenolate photooxidation is integral to a range of biological processes, yet the mechanism of electron ejection has been disputed. Here, we combine femtosecond transient absorption spectroscopy, liquid-microjet photoelectron spectroscopy and high-level quantum chemistry calculations to investigate the photooxidation dynamics of aqueous phenolate following excitation at a range of wavelengths, from the onset of the S0-S1 absorption band to the peak of the S0-S2 band. We find that for λ ≥ 266 nm, electron ejection occurs from the S1 state into the continuum associated with the contact pair in which the PhO˙ radical is in its ground electronic state. In contrast, we find that for λ ≤ 257 nm, electron ejection also occurs into continua associated with contact pairs containing electronically excited PhO˙ radicals and that these contact pairs have faster recombination times than those containing PhO˙ radicals in their ground electronic state.

| S-EPMC10034221 | biostudies-literature

Taurine ameliorates particulate matter-induced emphysema by switching on mitochondrial NADH dehydrogenase genes.

Project description:Chronic obstructive pulmonary disease (COPD) has been linked to particulate matter (PM) exposure. Using transcriptomic analysis, we demonstrate that diesel exhaust particles, one of the major sources of particulate emission, down-regulated genes located in mitochondrial complexes I and V and induced experimental COPD in a mouse model. 1-Nitropyrene was identified as a major toxic component of PM-induced COPD. In the panel study, COPD patients were found to be more susceptible to PM than individuals with normal lung function due to an increased inflammatory response. Mechanistically, exposure to PM in human bronchial epithelial cells led to a decline in CCAAT/enhancer-binding protein alpha (C/EBP?), which triggered aberrant expression of NADH dehydrogenase genes and ultimately led to enhanced autophagy. ATG7-deficient mice, which have lower autophagy rates, were protected from PM-induced experimental COPD. Using metabolomics analysis, we further established that treatment with taurine and 3-methyladenine completely restored mitochondrial gene expression levels, thereby ameliorating the PM-induced emphysema. Our studies suggest a potential therapeutic intervention for the C/EBP?/mitochondria/autophagy axis in PM-induced COPD.

| S-EPMC5692577 | biostudies-literature

Metallo-responsive switching between hexadecameric and octameric supramolecular G-quadruplexes.

Project description:We report the metallo-responsive high fidelity switching between hexadecameric and octameric supramolecular G-quadruplexes triggered by a change in the metal cation promoter from potassium to strontium, respectively.

| S-EPMC3364541 | biostudies-literature

Impact of charge switching stimuli on supramolecular perylene monoimide assemblies.

Project description:The development of stimuli-responsive amphiphilic supramolecular nanostructures is an attractive target for systems based on light-absorbing chromophores that can function as photosensitizers in water. We report here on a water soluble supramolecular carboxylated perylene monoimide system in which charge can be switched significantly by a change in pH. This was accomplished by substituting the perylene core with an ionizable hydroxyl group. In acidic environments, crystalline supramolecular nanoribbons with dimensions on the order of 500 × 50 × 2 nm form readily, while in basic solution the additional electrostatic repulsion of the ionized hydroxyl reduces assemblies to very small dimensions on the order of only several nanometers. The HOMO/LUMO levels were also found to be sensitive to pH; in acidic media the HOMO/LUMO levels are -5.65 and -3.70 eV respectively versus vacuum, whereas is in basic conditions they are -4.90 and -3.33 eV, respectively. Utilizing the assemblies as photosensitizers in photocatalytic production of hydrogen with [Mo3S13]2- as a catalyst at a pH of 4, H2 was generated with a turnover number of 125 after 18 hours. Charge switching the assemblies at a pH of 9-10 and using an iron porphyrin catalyst, protons could again be reduced to hydrogen and CO2 was reduced to CO with a turnover number of 30. The system investigated offers an example of dynamic photosensitizing assemblies that can drive reactions in both acidic and basic media.

| S-EPMC6568310 | biostudies-literature

The mechanism of catalysis by type-II NADH:quinone oxidoreductases.

Project description:Type II NADH:quinone oxidoreductase (NDH-2) is central to the respiratory chains of many organisms. It is not present in mammals so may be exploited as an antimicrobial drug target or used as a substitute for dysfunctional respiratory complex I in neuromuscular disorders. NDH-2 is a single-subunit monotopic membrane protein with just a flavin cofactor, yet no consensus exists on its mechanism. Here, we use steady-state and pre-steady-state kinetics combined with mutagenesis and structural studies to determine the mechanism of NDH-2 from Caldalkalibacillus thermarum. We show that the two substrate reactions occur independently, at different sites, and regardless of the occupancy of the partner site. We conclude that the reaction pathway is determined stochastically, by the substrate/product concentrations and dissociation constants, and can follow either a ping-pong or ternary mechanism. This mechanistic versatility provides a unified explanation for all extant data and a new foundation for the development of therapeutic strategies.

| S-EPMC5220320 | biostudies-literature

Cooperative supramolecular polymers with anthracene?endoperoxide photo-switching for fluorescent anti-counterfeiting.

Project description:Innovative technologies are highly pursued for the detection and avoidance of counterfeiting in modern information society. Herein, we report the construction of photo-responsive supramolecular polymers toward fluorescent anti-counterfeit applications, by taking advantage of multicycle anthracene?endoperoxide switching properties. Due to ?-metalation effect, photo-oxygenation of anthracene to endoperoxide is proceeded under the mild visible light irradiation conditions, while the backward conversion occurs spontaneously at room temperature. Supramolecular polymers are formed with cooperative nucleation?elongation mechanism, which facilitate fluorescence resonance energy transfer process via two-component co-assembly strategy. Fluorescence resonance energy transfer efficiency is delicately regulated by either light-triggered anthracene?endoperoxide conversion or vapor-induced monomer-polymer transition, leading to high-contrast fluorescent changes among three different states. On this basis, dual-mode anti-counterfeiting patterns have been successfully fabricated via inkjet printing techniques. Hence, cooperative supramolecular polymerization of photo-fluorochromic molecules represents an efficient approach toward high-performance anti-counterfeit materials with enhanced security reliability, fast response, and ease of operation.

| S-EPMC6162237 | biostudies-literature

Activation and Switching of Supramolecular Chemical Signals in Multi-Output Microfluidic Devices.

Project description:In this study, we report on the developing of a continuous microfluidic reaction device that allows selective activation of polyelectrolyte-surfactant chemical signals in microflows and switches them between multiple outputs. A numerical model was developed for convection-diffusion reaction processes in reactive polymer-colloid microfluidic flows. Matlab scripts and scaling laws were developed for this model to predict reaction initiation and completion conditions in microfluidic devices and the location of the reaction front. The model allows the optimization of microfluidic device geometry and the setting of operation modes that provide release of the reaction product through specific outputs. Representing a chemical signal, polyelectrolyte-surfactant reaction products create various logic gate states at microfluidic chip outputs. Such systems may have potential as biochemical signal transmitters in organ-on-chip applications or chemical logic gates in cascaded microfluidic devices.

| S-EPMC9611873 | biostudies-literature

Mechanism of magnetic relaxation switching sensing.

Project description:Magnetic relaxation switching (MRSw) assays that employ target-induced aggregation (or disaggregation) of magnetic nanoparticles (MNPs) can be used to detect a wide range of biomolecules. The precise working mechanisms, however, remain poorly understood, often leading to confounding interpretation. We herein present a systematic and comprehensive characterization of MRSw sensing. By using different types of MNPs with varying physical properties, we analyzed the nature and transverse relaxation modes for MRSw detection. The study found that clustered MNPs are universally in a diffusion-limited fractal state (dimension of ~2.4). Importantly, a new model for transverse relaxation was constructed that accurately recapitulates observed MRSw phenomena and predicts the MRSw detection sensitivities and dynamic ranges.

| S-EPMC3429660 | biostudies-literature

Optical switching of dipolar interactions on proteins.

Project description:This work shows that optical switching between the spiro (SP) and merocyanine (MC) states of different photochromes specifically labeled to G-actin can be used to rapidly and reversibly modulate specific dipolar interactions within the conjugate. Members of a common spirobenzopyran photochrome and a related spironaphthoxazine that differ only in the locations of their alkylating groups were selectively labeled to Cys-374 on G-actin. The nature of MC and SP interactions within G-actin was investigated by using optical spectroscopy. The average absorption energy of the highly polarized MC is sensitive to interactions with polar groups on solvents and G-actin; the average absorption energy of the corresponding SP state was found to be relatively constant, consistent with its lower dipole moment compared with MC (5 and 20 D, respectively). Alternate excitation of spirobenzopyran G-actin conjugates with 365 and 546 nm leads to rapid transitions from the SP to MC states and MC to SP states, respectively; optical switching within spirobenzopyran-G-actin occurs with high fidelity and the recovery of specific dipolar interactions between the protein and the MC and SP states. The difference in the free energy for specific dipolar interactions between different MC states within G-actin (6 kcal/mol) is similar to that found for complexes of G-actin and its regulatory proteins. We propose, therefore, that optical switching between SP and MC within an appropriately labeled conjugate could be used to inhibit a functional interaction with a ligand in the MC, but not the SP, state.

| S-EPMC555691 | biostudies-literature

OmicsDI is part of the ELIXIR infrastructure

OmicsDI is an Elixir interoperability service. Learn more ›

Tweets

OmicsDI Databases

PRIDE
PeptideAtlas
MassIVE
JPOST Repository
Physiome Model Repository

EGA
EVA
ENA
LINCS
PAXDB
Cell Collective

MetaboLights
Metabolomics Workbench
MetabolomeExpress
GNPS
BioModels
FAIRDOMHub

ArrayExpress
dbGaP
ExpressionAtlas
GEO
NODE

Information

Databases
Help
API
Contact us
Code on GitHub
Terms of use
Submit Data