Search results for "Multidisciplinary"

Production of soluble eukaryotic recombinant proteins in E. coli is favoured in early log-phase cultures induced at low temperature

2013

Abstract Background Producing recombinant plant proteins expressed in Escherichia coli produce in high yields and in a soluble and functional form can be difficult. Under overexpression conditions, proteins frequently accumulate as insoluble aggregates (inclusion bodies) within the producing bacteria. We evaluated how the initial culture density, temperature and duration of the expression stage affect the production of some eukaryotic enzymes in E. coli. Findings A high yield of active soluble proteins was obtained by combining early-log phase cultures and low temperatures for protein induction. When IPTG was added at OD600 = 0.1 and cultures were maintained at 4°C for 48-72 h, the soluble …

Comparative analysis of the coordinated motion of Hsp70s from different organelles observed by single-molecule three-color FRET.

2021

Cellular function depends on the correct folding of proteins inside the cell. Heat-shock proteins 70 (Hsp70s), being among the first molecular chaperones binding to nascently translated proteins, aid in protein folding and transport. They undergo large, coordinated intra- and interdomain structural rearrangements mediated by allosteric interactions. Here, we applied a three-color single-molecule Forster resonance energy transfer (FRET) combined with three-color photon distribution analysis to compare the conformational cycle of the Hsp70 chaperones DnaK, Ssc1, and BiP. By capturing three distances simultaneously, we can identify coordinated structural changes during the functional cycle. Be…

"Dormant" secondary metal-alkyl complexes are not omnipresent.

2006

This theoretical study was inspired by the perpetual debate over the so-called “dormancy” of the active sites in propylene polymerization, i.e., a drop in their activity after a regioerror (2,1-insertion), which was reported to occur in many (although not all) catalytic systems. To explore the range of possible situations, we have selected two homogeneous systems of fundamentally different structure: an octahedral system of C 2 symmetry with a tetradentate O N N O ligand and a bridged indenyl catalyst. This choice was not accidental; it is in these two systems where the experimentalists cannot reach a consensus about dormancy. Our density-functional theory calculations explain why in certa…

2013

Re-canalization of cerebral vessels in ischemic stroke is pivotal to rescue dysfunctional brain areas that are exposed to moderate hypoxia within the penumbra from irreversible cell death. Goal of the present study was to evaluate the effect of moderate hypoxia followed by reoxygenation (MHR) on the evolution of reactive oxygen species (ROS) and blood-brain barrier (BBB) integrity in brain endothelial cells (BEC). BBB integrity was assessed in BEC in vitro and in microvessels of the guinea pig whole brain in situ preparation. Probes were exposed to MHR (2 hours 67-70 mmHg O2, 3 hours reoxygenation, BEC) or towards occlusion of the arteria cerebri media (MCAO) with or without subsequent repe…

Generalized synthesis of periodic surfactant/inorganic composite materials

1994

THE recent synthesis of silica-based mesoporous materials1,2 by the cooperative assembly of periodic inorganic and surfactant-based structures has attracted great interest because it extends the range of molecular-sieve materials into the very-large-pore regime. If the synthetic approach can be generalized to transition-metal oxide mesostructures, the resulting nanocomposite materials might find applications in electrochromic or solid-electrolyte devices3,4, as high-surface-area redox catalysts5 and as substrates for biochemical separations. We have proposed recently6 that the matching of charge density at the surfactant/inorganic interfaces governs the assembly process; such co-organizatio…

Conservation of amino-acid chromatograms.

1951

IN filter-paper partition chromatography, the ninhydrin reaction has been used almost exclusively for the identification and quantitative assay of amino-acids. One of the chief disadvantages of the blue pigment formed in this reaction is its rapid fading on filter-paper chromatograms. This makes it difficult to construct permanent or semi-permanent reference maps from which not only the type of amino-acid, but also the approximate quantity of the unknown mixture, can be deduced.

Concentration-Dependent Antioxidant/Pro-Oxidant Activity of Ascorbic Acid in Chickens

2012

С vitamīns piedalās daudzos vielmaiņas procesos. Tas stiprina organisma imūnsistēmu, piedalās bioloģiskās oksidēšanās un reducēšanās procesos. Askorbīnskābe un dehidroaskorbīnskābe veido redoks sistēmu un ir saistītas ar glutationa sistēmu. Dažādu stresu ietekmē askorbīnskābes koncentrācija audos samazinās. Tādēļ barību vajag bagātināt ar šo vitamīnu. Darba mērķis bija pētīt dažādus oksidatīvā stresa biomarķierus cāļu organismā, kadmija akumulāciju orgānos, imūnsistēmas aktivitāti un nieru funkcijas izmaiņas askorbīnskābes ietekmē atkarībā no tās koncentrācijas barībā. Eksperimentos izmantojām vienu dienu vecus Lohmann Brown gailīšus, kurus sadalījām piecās analogās grupās. Cāļi saņēma komb…

2013

Nitric oxide, produced by the neuronal nitric oxide synthase (nNOS) from L-arginine is an important second messenger molecule in the central nervous system: It influences the synthesis and release of neurotransmitters and plays an important role in long-term potentiation, long-term depression and neuroendocrine secretion. However, under certain pathological conditions such as Alzheimer’s or Parkinson’s disease, stroke and multiple sclerosis, excessive NO production can lead to tissue damage. It is thus desirable to control NO production in these situations. So far, little is known about the substrate supply to human nNOS as a determinant of its activity. Measuring bioactive NO via cGMP form…

Is “I-DNA” derived from Nuclear DNA ?

1970

On the basis of double radioactive labelling and buoyant density studies, it is concluded that “I-DNA” is not a separate entity from nuclear DNA but may be an artefact derived from it.

White Phosphorus Is Air-Stable Within a Self-Assembled Tetrahedral Capsule

2009

Molecular Fire Quencher Cage-shaped molecular assemblies can regulate the reactivity of smaller molecules trapped within them. Mal et al. (p. 1697 ) extend this approach to enable the protection of elemental white phosphorus (P 4 ), a substance that rapidly ignites on contact with oxygen. The tetrahedral cages self-assemble in aqueous solution through coordination of six ligands to four iron ions, and efficiently capture phosphorus from a suspension. The water-soluble host-guest constructs were stable in air for at least 4 months, but released intact P 4 rapidly on displacement by added benzene.