Search results for "protons"
showing 10 items of 158 documents
Exploration of the Activation Mechanism of the Epigenetic Regulator MLL3: A QM/MM Study
2021
The mixed lineage leukemia 3 or MLL3 is the enzyme in charge of the writing of an epigenetic mark through the methylation of lysine 4 from the N-terminal domain of histone 3 and its deregulation has been related to several cancer lines. An interesting feature of this enzyme comes from its regulation mechanism, which involves its binding to an activating dimer before it can be catalytically functional. Once the trimer is formed, the reaction mechanism proceeds through the deprotonation of the lysine followed by the methyl-transfer reaction. Here we present a detailed exploration of the activation mechanism through a QM/MM approach focusing on both steps of the reaction, aiming to provide new…
Application of 1H NMR-based serum metabolomic studies for monitoring female patients with rheumatoid arthritis
2015
AbstractRheumatoid arthritis is a chronic autoimmune-based inflammatory disease that leads to progressive joint degeneration, disability, and an increased risk of cardiovascular complications, which is the main cause of mortality in this population of patients. Although several biomarkers are routinely used in the management of rheumatoid arthritis, there is a high demand for novel biomarkers to further improve the early diagnosis of rheumatoid arthritis, stratification of patients, and the prediction of a better response to a specific therapy.In this study, the metabolomics approach was used to provide relevant biomarkers to improve diagnostic accuracy, define prognosis and predict and mon…
Metabolite identification in human liver needle biopsies by high-resolution magic angle spinning1H NMR spectroscopy
2006
High-resolution magic angle spinning (HR-MAS) 1 H NMR spectroscopy of intact human liver needle biopsies has not been previously reported. HR-MAS NMR spectra collected on 17 specimens with tissue amounts between � 0.5 and 12 mg showed very good spectral resolution and signal-to-noise ratios. One-dimensional 1 H spectra revealed many intense signals corresponding to cellular metabolites. In addition, some high molecular weight metabolites, such as glycogen and mobile fatty acids, could be observed in some spectra. Resonance assignments for 22 metabolites were obtained by combining the analysis of three different types of 1D 1 H spectral editing, such as T2 filtering or the nuclear Overhauser…
1H and 13C HR-MAS spectroscopy of intact biopsy samples ex vivo and in vivo 1H MRS study of human high grade gliomas.
2004
High-resolution magic angle spinning (HR-MAS) one- and two-dimensional 1H and 13C nuclear magnetic resonance (NMR) spectroscopy has been used to study intact glioblastoma (GBM) brain tumour tissue. The results were compared with in vitro chemical extract and in vivo spectra. The resolution of 1H one-dimensional, 1H TOCSY and 13C HSQC HR-MAS spectra is comparable to that obtained on perchloric extracts. 13C HSQC HR-MAS spectra have been particularly useful for the identification of 37 different metabolites in intact biopsy tumours, excluding water and DSS components. To our knowledge, this is the most detailed assignment of biochemical compounds obtained in intact human tissue, in particular…
Study of hypothalamic metabolism in cluster headache by proton MR spectroscopy
2006
The authors used 1H-MRS to investigate hypothalamic metabolism in 26 patients with cluster headache (CH) and 12 healthy subjects. Hypothalamic N-acetylaspartate/creatine was reduced in patients with CH vs controls (p < 0.01). Dividing the patients into episodic CH outside- and in-cluster periods and chronic CH, the hypothalamic N-acetylaspartate/creatine in all three subgroups of patients was reduced. The reduction of the neuronal marker N-acetylaspartate is consistent with hypothalamic neuronal dysfunction in patients with CH.
Alanine EPR pellets for dosimetry of clinical proton and carbon ion beams
2015
The main gol of the present work is to investigate the response behaviour of alanine EPR pellets in clinical proton anc carbon ion beams. Proton irradiations were carried out at PSI (Switzerland) using both passive and active scattering modality, whereas, C ions irradiation were performed at GSI (Germany) adopting the raster scanning modality.
Modelling of proton and metal exchange in the alginate biopolymer.
2005
Acid-base behaviour of a commercial sodium alginate extracted from brown seaweed (Macrocystis pyrifera) has been investigated at different ionic strengths (0.1or=I/mol l(-1)or=1.0) and in different supporting electrolytes (Et4NI, NaCl, KCl, LiCl, NaCl+MgCl2), with the aim of examining the influence of ionic medium on the proton-binding capacity and of quantifying the strength of interaction with light metal ions in the perspective of speciation studies in natural aqueous systems. Potentiometric ([H+]-glass electrode) and titration calorimetric data were expressed as a function of the dissociation degree (alpha) using different models (Henderson-Hasselbalch modified, Högfeldt three parameter…
“AND” luminescent “reactive” molecular logic gates: a gateway to multi-analyte bioimaging and biosensing
2014
This review outlines examples that illustrate a recent and highly innovative concept in the field of (bio)molecular sensing, namely the simultaneous multi-analyte detection using "reactive" luminescent probes that are able to produce an optical signal only in response to multiple (bio)chemical inputs and through covalent chemical reactions with target (bio)analytes. Unlike conventional "AND" molecular logic gates based on supramolecular photochemical mechanisms, these unusual "smart" optical (bio)probes are suitable tools to track the rise and fall of a wider range of biologically relevant analytes, in complex media and with higher selectivity. The potential utility of this concept for in v…
Proton coupled electron transfer of ubiquinone Q2 incorporated in a self-assembled monolayer.
2011
We present a complete study of the reduction of ubiquinone Q(2) (UQ(2)) in simpler aqueous medium, over a pH range of 2.5 to 12.5. The short isoprenic chain ubiquinones (UQ(2)) were incorporated in a self-assembled monolayer. Under these conditions, the global 2e(-) electrochemical reaction can be described on the basis of a nine-member square scheme. The thermodynamic constants of the system were determined. The global 2e(-) process is controlled by the uptake of the second electron. The elementary electrochemical rate constants obtained by fitting of the experimental rate constant were k(s4) = 1.5 s(-1) for QH˙(+)(2)↔ QH(2), k(s5) = 1.5 s(-1) for QH˙↔ QH(-) and k(s6) = 1 s(-1) for Q˙(-)↔ …
Improved limit on the directly measured antiproton lifetime
2017
Continuous monitoring of a cloud of antiprotons stored in a Penning trap for 405 days enables us to set an improved limit on the directly measured antiproton lifetime. From our measurements we extract a storage time of $3.15\times {10}^{8}$ equivalent antiproton-seconds, resulting in a lower lifetime limit of ${\tau }_{\bar{{\rm{p}}}}\gt 10.2\,{\rm{a}}$ with a confidence level of $68 \% $. This result improves the limit on charge-parity-time violation in antiproton decays based on direct observation by a factor of 7.