Anti-platelet activity of a three-finger toxin (3FTx) from Indian monocled cobra (Naja kaouthia) venom

A low molecular weight anti-platelet peptide (6.9 kDa) has been purified from Naja kaouthia venom and was named KT-6.9. MALDI-TOF/TOF mass spectrometry analysis revealed the homology of KT-6.9 peptide sequence with many three finger toxin family members. KT-6.9 inhibited human platelet aggregation process in a dose dependent manner. It has inhibited ADP, thrombin and arachidonic acid induced platelet aggregation process in dose dependent manner, but did not inhibit collagen and ristocetin induced platelet aggregation. Strong inhibition (70%) of the ADP induced platelet aggregation by KT-6.9 suggests competition with ADP for its receptors on platelet surface. Anti-platelet activity of KT-6.9 was found to be 25 times stronger than that of anti-platelet drug clopidogrel. Binding of KT-6.9 to platelet surface was confirmed by surface plasma resonance analysis using BIAcore X100. Binding was also observed by a modified sandwich ELISA method using anti-KT-6.9 antibodies. KT-6.9 is probably the first 3FTx from Indian monocled cobra venom reported as a platelet aggregation inhibitor.     

Synthesis of highly fluorescent nitrogen and phosphorus doped carbon dots for the detection of Fe3+ ions in cancer cells

Highly fluorescent nitrogen and phosphorus‐doped carbon dots with a quantum yield 59% have been successfully synthesized from citric acid and di‐ammonium hydrogen phosphate by single step hydrothermal method. The synthesized carbon dots have high solubility as well as stability in aqueous medium. The as‐obtained carbon dots are well monodispersed with particle sizes 1.5–4 nm. Owing to a good tunable fluorescence property and biocompatibility, the carbon dots were applied for intercellular sensing of Fe³⁺ ions as well as cancer cell imaging. Copyright © 2015 John Wiley & Sons, Ltd.     

A Preliminary Study on Oxya fuscovittata (Marschall) as an Alternative Nutrient Supplement in the Diets of Poecillia sphenops (Valenciennes)

Growth of the ornamental fish industry is being hindered by the scarcity of low cost feed; hence alternative protein supplements should be explored. In this context the present study aims to evaluate whether the grasshopper Oxya fuscovittata could be used as a supplement for fish meal in the diets of Poecillia sphenops, which is one of the most common ornamental fishes worldwide. The present work is divided into three phases: In the first phase proximate composition of the grasshopper is obtained and five diets are prepared where fish meal is gradually replaced by Oxya meal and named as control, D1, D2, D3 and D4. All the diets are formulated on iso-nitrogenous basis where the protein percentage is fixed at 400 g/kg. The second phase deals with feeding trial and in the third phase all the data of the feeding trial are subjected to a linear model. The feeding trial shows that the control, D1 and D2 fed fishes have almost similar results. The linear model proves that the variation in the indices are mainly due to replacement of fish meal by Oxya meal, not due to the variations of rice husk and mustard oil cake that are also used to formulate the diets of the present study. From the results two Oxya supplemented diets, i.e. D1 and D2 are proved to be almost equivalent to the control diet. Hence it is concluded that Oxya meal is able to replace 25% to 50% of fish meal from the diets of P. sphenops.     

Insilico analysis and molecular docking of resuscitation promoting factor B (RpfB) protein of Mycobacterium tuberculosis

Invulnerability of Mycobacterium tuberculosis to various drugs and its persistency has stood as a hurdle in the race against eradication of the pathogenecity of the bacteria. Identification of novel antituberculosis compounds is highly demanding as the available drugs are resistant. The ability of the bacteria to surpass the body''s defenses and adapt itself to survive for disease reactivation is contributed by secreted proteins called resuscitating promoting factors (Rpfs). These factors aid in virulence and resuscitation from dormancy of the bacteria. Sequence analysis of RpfB was performed and compounds were first screened for toxicity and high-throughput virtual screening eliminating the toxic compounds. To understand the mechanism of ligand binding and interaction, molecular docking was performed for the compounds passing through the filter resulting with better docking studies predicting the possible binding mode of the inhibitors to the protein. Of all the active residues the binding conformation shows that residues Arg194, Arg196, Glu242, and Asn244 of the RpfB protein play vital role in the enzyme activity and interacts with the ligands. Promising compounds have been identified in the current study, thus holding promise for design of antituberculosis drugs.     

Chemotherapeutic potential of 9-phenyl acridine: biophysical studies on its binding to DNA

Acridines and their derivatives are well-known probes for nucleic acids as well as being relevant in the field of drug development to establish new chemotherapeutic agents. We have shown from molecular modelling studies that 9-phenyl acridine and some of its derivatives can act as inhibitors of topoisomerase I and thus have potential to act as anticancer agents. Rational design of new compounds for therapeutics requires knowledge about their structural stability and interactions with various cellular macromolecules. In this regard it is important to know how these molecules would interact with DNA. Here we report the interaction of 9-phenyl acridine (ACPH) with calf thymus DNA (CT-DNA) based on various biophysical and molecular modelling studies. Spectrophotometric studies indicated that ACPH binds to CT-DNA. DNA melting studies revealed that binding of ACPH to CT-DNA resulted in a small increase in melting temperature, which is unlikely in case of classical intercalator; rather, it indicates external binding. Viscosity measurements show that ACPH exhibits groove binding. Competitive binding of ACPH to CT-DNA pre-bound to ethidium bromide (EB) showed slow quenching. Measurement of the binding constant of ACPH by fluorescent intercalator displacement (FID) assay corroborated the notion that there was groove binding. Molecular modelling studies also supported this finding. Results indicate that binding of ACPH is through partial intercalation in the minor groove of DNA.     

Active site driven ligand design: an evolutionary approach

An evolutionary approach for designing a ligand molecule that can bind to the active site of a target protein is described in this article. An earlier attempt in this regard assumed a fixed tree structure of the ligand on both sides of the pharmacophore, and used a genetic algorithm for optimizing the van der Waals energy. However, it is evident that knowledge about the size of the tree is difficult to obtain an a priori. Moreover, it will also change from one active site to another. This limitation is overcome in the present article by using variable string length genetic algorithm (VGA) for evolving an appropriate arrangement of the basic functional units of the molecule to be designed, whose size may now vary. The crossover and mutation operators are appropriately redesigned in order to tackle the concept of variable length chromosomes. Once the geometry of the molecule is obtained, the possible three-dimensional structure and its docking energy is determined. Results are demonstrated for five different target proteins both numerically and pictorially. It is found that not only does the molecule designed using variable length representation, in general, have lower energy values, the docking energies are also lower, as compared to the molecule evolved using fixed size representation.     

An Autoinhibited State in the Structure of Thermotoga maritima NusG

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Highlights? Thermotoga maritima NusG shows a dynamic intramolecular NTD-CTD interaction ? The NTD-CTD interaction hides the binding surfaces for RNA polymerase, S10, and Rho ? Domain interaction contributes to thermostability ? Thermotoga maritima NusG does not complement a NusG-deficient E. coli strain