Dichlorosilylene: Rate constant for the gas-phase reaction with nitric oxide

Using the recently detected intense UV absorption spectrum of it has been established that SiCl₂ reacts with nitric oxide in the gas phase with a bimolecular rate constant, k(SiCl₂+NO), of (1.6±0.1)×10⁹ M⁻¹s⁻¹ at 25°C.     

Fluorescein dye derivative: Synthesis,characterization, quantum chemical and promising antimicrobial activity studies

The dimethyl sulfite as an alkylating as well as alkoxylating reagent is well known in synthetic organic as well as organometallic chemistry for a long time. Herein, we have utilized dimethyl sulfite as an alkylating reagent and reacted with fluorescein derivative, N-fluorescein-lactam-hydrazine ( B ). This reaction leads to the generation of tetramethylated fluorescein lactam hydrazine ( A ). The newly designed and synthesized molecule ( A ) has been characterized by ¹H, ¹³C NMR and HRMS data. The antimicrobial activity of the synthesized alkylated fluorescein derivative has been tested against E. coli, P. aeruginosa, Salmonella typhimurium and S. aureus microbial agents. Time-kill assay results also confirmed that fluorescein derivative is a potent antimicrobial agent and revealed that the time-kill assay of fluorescein derivative is value-added than the well-known antibiotic. In addition, quantum chemical study was used to analyze its activity trend and correlated with the experimental data. The computed results of DFT revealed that the lipophilicity as well as the LUMO-HOMO band gap (ΔE_LUMO-HOMO = 4.75 eV) of compound A make it more suitable as an antimicrobial agent to match with in vitro antimicrobial experimental results. The MIC and MBC values of compound A were observed to be lower in contrast to fluorescein and ampicillin for all the tested bacterial strains, which were approximately 3- to 4-fold lower than MIC and MBC values of the later. Results obtained from the study clearly indicate that compound A has better antimicrobial and bactericidal activity in comparison to ampicillin and fluorescein. Synthesized compound can be a better substitute of traditionally used antibiotics, Ampicillin.     

Disordered proteins and network disorder in network descriptions of protein structure, dynamics and function: hypotheses and a comprehensive review

During the last decade, network approaches became a powerful tool to describe protein structure and dynamics. Here we review the links between disordered proteins and the associated networks, and describe the consequences of local, mesoscopic and global network disorder on changes in protein structure and dynamics. We introduce a new classification of protein networks into 'cumulus-type', i.e., those similar to puffy (white) clouds, and 'stratus-type', i.e., those similar to flat, dense (dark) low-lying clouds, and relate these network types to protein disorder dynamics and to differences in energy transmission processes. In the first class, there is limited overlap between the modules, which implies higher rigidity of the individual units; there the conformational changes can be described by an 'energy transfer' mechanism. In the second class, the topology presents a compact structure with significant overlap between the modules; there the conformational changes can be described by 'multi-trajectories'; that is, multiple highly populated pathways. We further propose that disordered protein regions evolved to help other protein segments reach 'rarely visited' but functionally-related states. We also show the role of disorder in 'spatial games' of amino acids; highlight the effects of intrinsically disordered proteins (IDPs) on cellular networks and list some possible studies linking protein disorder and protein structure networks.     

A mechanistic study of sialic acid mutarotation: implications for mutarotase enzymes

The mutarotation of N-acetylneuraminic acid (Neu5Ac) proceeds by four kinetically distinct pathways: (i) the acid-catalyzed reaction of neutral Neu5Ac; (ii) the spontaneous reaction of the carboxylic acid (the kinetically equivalent acid-catalyzed reaction on the anion being ruled out by the solvent deuterium kinetic isotope effect of 3.74 ± 0.68); (iii) a spontaneous, water-catalyzed, reaction of the anion; and (iv) a specific-base catalyzed reaction of the anion. The magnitude of the solvent kinetic isotope effect, k(H2O)/k(D2O) = 4.48 ± 0.74 is consistent with a ring-opening transition state in which a water molecule is deprotonating the anomeric hydroxyl group in concert with strengthening solvation of the ring oxygen atom. The mechanistic implications for Neu5Ac mutarotases are discussed.     

Annealing of heavy ion radiation damage in muscovite mica and concept of single activation energy

Abstract

Annealing behaviour of heavy ion radiation damage in muscovite is studied at different temperatures. The activation energies E_a for annealing of heavy ion tracks of different energies, viz. ⁹³Nb(18.0 MeVn ^?1), ²⁰⁸Pb(17.0MeVn ^?1), ²³⁸U(10.0MeVn ^?1) and ²⁵²Cf(fission fragments), are found to be the same (～0.97 eV). The concept of a single activation energy as an intrinsic property of the detector seems to be fully justified.     

Microwave Induced 1,3-Depolar Cycloaddition Reactions of Nitrones

1,3-Dipolar cycloaddition reactions involving unreactive nitrones have been carried out successfully under microwave irradiations. The reaction of nitrones 1 and alkene 2 proceeded regiospecifically at atmospheric pressure and the corresponding isoxazolidines 3 were obtained in high yields.     

A Facile Transfer of Dicyano Methylene Group Between Arylidenemalononitrile and Aldehyde

Arylidenemalononitrile undergoes facile exchange of dicyano methylene group with β-formyl steroidal enamide as well as aromatic aldehydes under mild base catalysed reaction.     

A New Efficient Commercial Iron Mediated Debromination of Aryl Substituted Vic-Dibromide

Debromination of vic-dibromides with commercially available metallic iron in a methanolic medium affords alkenes and alkynes in excellent yields.     

Machine learning-based modeling to predict inhibitors of acetylcholinesterase

Molecular Diversity - Acetylcholinesterase enzyme is responsible for the degradation of acetylcholine and is an important drug target for the treatment of Alzheimer’s disease. When this...