Search results for "isothermal"
showing 10 items of 212 documents
Mg2+ binding triggers rearrangement of the IM30 ring structure, resulting in augmented exposure of hydrophobic surfaces competent for membrane binding
2018
The "inner membrane-associated protein of 30 kDa" (IM30), also known as "vesicle-inducing protein in plastids 1" (Vipp1), is found in the majority of photosynthetic organisms that use oxygen as an energy source, and its occurrence appears to be coupled to the existence of thylakoid membranes in cyanobacteria and chloroplasts. IM30 is most likely involved in thylakoid membrane biogenesis and/or maintenance, and has recently been shown to function as a membrane fusion protein in presence of Mg2+ However, the precise role of Mg2+ in this process and its impact on the structure and function of IM30 remains unknown. Here, we show that Mg2+ binds directly to IM30 with a binding affinity of ∼1 mm …
Direct and Rapid Detection and Quantification of Oenococcus oeni Cells in Wine by Cells-LAMP and Cells-qLAMP
2018
Fast detection and enumeration of Oenococcus oeni in winemaking are necessary to determine whether malolactic fermentation (MLF) is likely to be performed or not and to decide if the use of a commercial starter is needed. In other wines, however, performing MLF can be detrimental for wine and should be avoided. The traditional identification and quantification of this bacteria using culture-dependent techniques in wine-related matrices require up to 14 days to yield results, which can be a very long time to perform possible enological operations. Loop-mediated isothermal amplification (LAMP) is a novel culture-independent technique that amplifies nucleic acid sequences under isothermal cond…
Kinetic evidence for interaction of TMPyP4 with two different G-quadruplex conformations of human telomeric DNA
2018
Background: Stabilization of G-quadruplex helices by small ligands has attracted growing attention because they inhibit the activity of the enzyme telomerase, which is overexpressed in> 80% cancer cells. TMPyP4, one of the most studied G-quadruplex ligands, is used as a model to show that the ligands can exhibit different binding features with different conformations of a human telomeric specific sequence. Methods: UV–Vis, FRET melting Assay, Isothermal Titration Calorimetry, Time-resolved Fluorescence lifetime, T-Jump and Molecular Dynamics. Results: TMPyP4 yields two different complexes with two Tel22 telomeric conformations in the presence of Na+ or K+. T-Jump kinetic experiments show th…
Quantitative analysis of the impact of a human pathogenic mutation on the CCT5 chaperonin subunit using a proxy archaeal ortholog
2017
The human chaperonin complex is a ~ 1 MDa nanomachine composed of two octameric rings formed from eight similar but non-identical subunits called CCT. Here, we are elucidating the mechanism of a heritable CCT5 subunit mutation that causes profound neuropathy in humans. In previous work, we introduced an equivalent mutation in an archaeal chaperonin that assembles into two octameric rings like in humans but in which all subunits are identical. We reported that the hexadecamer formed by the mutant subunit is unstable with impaired chaperoning functions. This study quantifies the loss of structural stability in the hexadecamer due to the pathogenic mutation, using differential scanning calorim…
Identification and structural characterization of LytU, a unique peptidoglycan endopeptidase from the lysostaphin family
2017
AbstractWe introduce LytU, a short member of the lysostaphin family of zinc-dependent pentaglycine endopeptidases. It is a potential antimicrobial agent for S. aureus infections and its gene transcription is highly upregulated upon antibiotic treatments along with other genes involved in cell wall synthesis. We found this enzyme to be responsible for the opening of the cell wall peptidoglycan layer during cell divisions in S. aureus. LytU is anchored in the plasma membrane with the active part residing in the periplasmic space. It has a unique Ile/Lys insertion at position 151 that resides in the catalytic site-neighbouring loop and is vital for the enzymatic activity but not affecting the …
Structural Basis of the High Affinity Interaction between the Alphavirus Nonstructural Protein-3 (nsP3) and the SH3 Domain of Amphiphysin-2
2016
We show that a peptide from Chikungunya virus nsP3 protein spanning residues 1728–1744 binds the amphiphysin-2 (BIN1) Src homology-3 (SH3) domain with an unusually high affinity (Kd 24 nM). Our NMR solution complex structure together with isothermal titration calorimetry data on several related viral and cellular peptide ligands reveal that this exceptional affinity originates from interactions between multiple basic residues in the target peptide and the extensive negatively charged binding surface of amphiphysin-2 SH3. Remarkably, these arginines show no fixed conformation in the complex structure, indicating that a transient or fluctuating polyelectrostatic interaction accounts for this …
Investigation on the Adsorption of N2 Ar, CO and CH4 on Aluminophosphates
1994
Abstract Adsorption isotherms at different temperatures and isothermal micro-calorimetric curves were measured for N2 Ar, CO, and CH4 on various molecular sieves as VPI-5, MCM-9, AlPO4-8, AlPO4-H, AlPO4-5, SAPO-5, AlPO4-39, AlPO4-C. It was shown that the isosteric heats of adsorption correlated with the pore-sizes of the studied molecular sieves.
Study and Modelling of the Vacuum Swing Adsorption (VSA) Process Employed in the Production of Oxygen
1999
An isothermal and non-equilibrium mathematical model was provided for the multi-component adsorption process. In addition, the software was developed for the VSA-based production of oxygen with the use of a CaX zeolite molecular sieve. The mathematical model and computer software were verified on the basis of experimental data. The study employed a test stand comprising two adsorption columns. The adsorption pressure P A = 150 and 135 kPa and desorption pressure P D = 20 kPa were adopted in the experiments. The tests produced oxygen with the purity of 90–94% O 2 (vol), at an efficiency of 55–73% and productivity of 570–850 kg O 2 per ton per day. The calculation results showed good consiste…
Evaluation of saliva as a complementary technique to the diagnosis of COVID-19:a systematic review
2021
Background Infectious disease coronavirus 2019 (COVID-19) is caused by the SARS-CoV-2 virus, and it mainly affects the upper respiratory tract. The gold standard for its diagnosis is real-time reverse transcription polymerase chain reaction (RT-qPCR) performed on a nasopharyngeal swab. In contrast, testing saliva has significant advantages as a diagnostic method. Material and Methods We searched for articles evaluating saliva as a diagnostic method for COVID-19 on the PUBMED/MEDLINE, WEB OF SCIENCE, COCHRANE, and SCIELO platforms. We initially found 233 articles and 20 were selected for inclusion following the Preferred Reporting Items for Systematic Reviews and Meta-Analyses protocol: 18 c…
Adsorption and diffusion of linear and dibranched C6 paraffins in a ZSM-5 zeolite
2002
The adsorption of n-hexane and 2,2-dimethylbutane on a commercial ZSM-5 zeolite is studied under isothermal and isobaric conditions. ZSM-5 exhibits two different behaviours with linear and dibranched alkanes. A substep at 4 molec.uc−1 is observed on the adsorption isotherm of n-hexane at 348 K. A singular adsorption-desorption process is evidenced on the adsorption isobar at 5.5 kPa with 2,2-dimethylbutane at a temperature close to 343 K when the sample is activated at 298 K under vacuum. The diffusivities have been determined by fitting directly the uptake curves with a numerical resolution of second Fick's law based on finite difference method. Microporous diffusion seems to be rate limit…