IN VITRO ANTIOXIDANT POTENTIAL OF WHOLE PLANT OF ANDROGRAPHIS ECHIOIDES (L.) NEES (ACANTHACEAE)

Objective: Antioxidant activity of petroleum ether, benzene, ethyl acetate, methanol and ethanol extracts of the whole plant of Andrographis echioides have been tested using various antioxidant model systems viz; DPPH (1,1-Diphenyl-2-picryl-hydrazyl), hydroxyl, superoxide, ABTS (2, 2'-Azino-Bis-3-Ethylbenzothiazoline-6-Sulfonic Acid) and reducing power.Methods: Total phenolic content was estimated by folin-ciocalteau method. Flavonoids were determined by Aluminium chloride method. In vitro antioxidant activity of petroleum ether, benzene, ethyl acetate, methanol and ethanol extracts was evaluated by studying DPPH (1,1-Diphenyl-2-picryl-hydrazyl) radical scavenging activity, hydroxyl radical scavenging activity, superoxide radical scavenging activity, ABTS radical cation scavenging activity and reducing power using the standard procedure.Results: The total phenolic and flavonoids in methanol extract were found to be 1.26g/100 g and 1.18 g/100 g respectively. The methanol extract of Andrographis echioides is found to possess DPPH, hydroxyl, superoxide and ABTS radical cation scavenging activity. The IC50 value of DPPH, hydroxyl, superoxide, and ABTS radical cation scavenging activity were found to be 49.11, 36.18, 37.13 and 38.15 mg/ml respectively. Like the antioxidant activity, reducing the power of the extract increases with increase in concentration.Conclusion: The finding indicated promising antioxidant activity of crude extracts of the above plant and needs further exploration for their effective are in the both modern and traditional system of medicines.Keywords: Antioxidant activity, DPPH, ABTS, Phenol, Flavonoid

Structural basis of human kinesin-8 function and inhibition

Kinesin motors play diverse roles in mitosis and are targets for anti-mitotic drugs. The clinical significance of these motors emphasizes the importance of understanding the molecular basis of their function. Equally, investigations into the modes of inhibition of these motors provide crucial information about their molecular mechanisms. Kif18A regulates spindle microtubules through its dual functionality – microtubule-based stepping and regulation of microtubule dynamics. We investigated the mechanism of Kif18A and its inhibition by the small molecule BTB-1. The Kif18A motor domain drives ATP-dependent plus-end microtubule gliding, and undergoes conformational changes consistent with canonical mechanisms of plus-end directed motility. The Kif18A motor domain also depolymerises microtubule plus and minus ends. BTB-1 inhibits both microtubule-based Kif18A activities. A reconstruction of BTB-1-bound, microtubule-bound Kif18A, in combination with computational modelling, identified an allosteric BTB-1 binding site near loop5, where it blocks the ATP-dependent conformational changes we characterised. Strikingly, BTB-1 binding is close to that of well-characterised Kif11 inhibitors that block tight microtubule binding, whereas BTB-1 traps Kif18A on the microtubule. Our work highlights a general mechanism of kinesin inhibition in which small molecule binding near loop5 prevents a range of conformational changes, blocking motor function

Mutations in the histone methyltransferase gene KMT2B cause complex early-onset dystonia.

Histone lysine methylation, mediated by mixed-lineage leukemia (MLL) proteins, is now known to be critical in the regulation of gene expression, genomic stability, cell cycle and nuclear architecture. Despite MLL proteins being postulated as essential for normal development, little is known about the specific functions of the different MLL lysine methyltransferases. Here we report heterozygous variants in the gene KMT2B (also known as MLL4) in 27 unrelated individuals with a complex progressive childhood-onset dystonia, often associated with a typical facial appearance and characteristic brain magnetic resonance imaging findings. Over time, the majority of affected individuals developed prominent cervical, cranial and laryngeal dystonia. Marked clinical benefit, including the restoration of independent ambulation in some cases, was observed following deep brain stimulation (DBS). These findings highlight a clinically recognizable and potentially treatable form of genetic dystonia, demonstrating the crucial role of KMT2B in the physiological control of voluntary movement.Funding for the project was provided by the Wellcome Trust for UK10K (WT091310) and DDD Study. The DDD study presents independent research commissioned by the Health Innovation Challenge Fund [grant number HICF-1009-003] - see www.ddduk.org/access.html for full acknowledgement. This work was supported in part by the Intramural Research Program of the National Human Genome Research Institute and the Common Fund, NIH Office of the Director. This work was supported in part by the German Ministry of Research and Education (grant nos. 01GS08160 and 01GS08167; German Mental Retardation Network) as part of the National Genome Research Network to A.R. and D.W. and by the Deutsche Forschungsgemeinschaft (AB393/2-2) to A.R. Brain expression data was provided by the UK Human Brain Expression Consortium (UKBEC), which comprises John A. Hardy, Mina Ryten, Michael Weale, Daniah Trabzuni, Adaikalavan Ramasamy, Colin Smith and Robert Walker, affiliated with UCL Institute of Neurology (J.H., M.R., D.T.), King’s College London (M.R., M.W., A.R.) and the University of Edinburgh (C.S., R.W.)

Assignment of PolyProline II Conformation and Analysis of Sequence – Structure Relationship

International audienceBACKGROUND: Secondary structures are elements of great importance in structural biology, biochemistry and bioinformatics. They are broadly composed of two repetitive structures namely α-helices and β-sheets, apart from turns, and the rest is associated to coil. These repetitive secondary structures have specific and conserved biophysical and geometric properties. PolyProline II (PPII) helix is yet another interesting repetitive structure which is less frequent and not usually associated with stabilizing interactions. Recent studies have shown that PPII frequency is higher than expected, and they could have an important role in protein - protein interactions. METHODOLOGY/PRINCIPAL FINDINGS: A major factor that limits the study of PPII is that its assignment cannot be carried out with the most commonly used secondary structure assignment methods (SSAMs). The purpose of this work is to propose a PPII assignment methodology that can be defined in the frame of DSSP secondary structure assignment. Considering the ambiguity in PPII assignments by different methods, a consensus assignment strategy was utilized. To define the most consensual rule of PPII assignment, three SSAMs that can assign PPII, were compared and analyzed. The assignment rule was defined to have a maximum coverage of all assignments made by these SSAMs. Not many constraints were added to the assignment and only PPII helices of at least 2 residues length are defined. CONCLUSIONS/SIGNIFICANCE: The simple rules designed in this study for characterizing PPII conformation, lead to the assignment of 5% of all amino as PPII. Sequence - structure relationships associated with PPII, defined by the different SSAMs, underline few striking differences. A specific study of amino acid preferences in their N and C-cap regions was carried out as their solvent accessibility and contact patterns. Thus the assignment of PPII can be coupled with DSSP and thus opens a simple way for further analysis in this field

Cryo-EM model validation recommendations based on outcomes of the 2019 EMDataResource challenge

This paper describes outcomes of the 2019 Cryo-EM Model Challenge. The goals were to (1) assess the quality of models that can be produced from cryogenic electron microscopy (cryo-EM) maps using current modeling software, (2) evaluate reproducibility of modeling results from different software developers and users and (3) compare performance of current metrics used for model evaluation, particularly Fit-to-Map metrics, with focus on near-atomic resolution. Our findings demonstrate the relatively high accuracy and reproducibility of cryo-EM models derived by 13 participating teams from four benchmark maps, including three forming a resolution series (1.8 to 3.1 Å). The results permit specific recommendations to be made about validating near-atomic cryo-EM structures both in the context of individual experiments and structure data archives such as the Protein Data Bank. We recommend the adoption of multiple scoring parameters to provide full and objective annotation and assessment of the model, reflective of the observed cryo-EM map density

Recent Advances in Calculating Space Charge Distribution by Processing the Signals Obtained Using the Thermal Step Method

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Dernières avancées de la méthode de l'onde thermique

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The Thermal Step Method for Space Charge Measurements under Applied dc Field

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