Binding of leucomycin and its derivatives to E. Coli ribosomes

Structure-activity relationships have been discussed for inhibition of [¹⁴C] erythromycin binding to Escherichia coli ribosomes by leucomycin and its acyl derivatives in the light of the Fujita-Ban de novo model. The group contributions of various substituents show that acylation at position 4″ of the mycarose moiety of leucomycin increases affinity for binding of leucomycins to ribosomes. It is also indicated that unlike at position 2' in mycaminose region a free hydroxyl at position 9 of the lactone ring is not important for binding to ribosomes.     

Linear free energy relationships implicate three modes of binding for fluoroaromatic inhibitors to a mutant of carbonic anhydrase II

[figure: see text] Linear free energy relationships between binding affinity and hydrophobicity for a library of fluoroaromatic inhibitors of F131V carbonic anhydrase II (CA) implicate three modes of interaction. X-ray crystal structures suggest that F131 interacts with fluoroaromatic inhibitors, while P202, on the opposite side of the active site cleft, serves as the site of the hydrophobic contact in the case of the F131V mutant. 2-Fluorinated compounds bind more tightly, perhaps due to the field effect of the nearby fluorine on the acidity of the amide proton.     

Finite element Galerkin Approach for a Computational Study of Arterial Flow

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Quantum chaos, thermalization and dissipation in nuclear systems

Nuclei have complex energy-level sequence with statistical properties in agreement with canonical random matrix theory. This agreement appears when the one-particle one-hole states are mixed completely with two-particle two-hole states. In the transition, there is a new universality which we present here, bringing about a relation between dynamics and statistics. We summarize also the role of chaos in thermalization and dissipation in isolated systems like nuclei. The methods used to bring forth this understanding emerge from random matrix theory, semiclassical physics, and the theory of dynamical systems.     

Manual and flow-injection spectrophotometric assay of thiols, based on their S-nitrosation

A general assay procedure for a wide variety of thiols is described. The technique has three steps: (1) formation of S-nitrosothiols with nitrous acid, (2) destruction of the excess of nitrous acid, (3) hydrolysis of the S-nitrosothiols with mercuric ions and subsequent formation of an azo-dye by means of the nitrous acid liberated. Both manual and flow-injection analysis (FIA) versions of the assay are described. Since the final step of the assay does not depend on the thiol assayed but only on the reaction of nitrous acid to form azo-dyes, the calibration graphs should be identical for all thiols. The manual system is about four times as sensitive as the FIA system, but the latter permits a high sample throughput and shows significantly lower sensitivity to interference by tryptophan. Though this general technique cannot be used for the assay of many sterically hindered thiols, it can be used for the assay of some protein thiol groups.     

An In Silico investigation for acyclovir and its derivatives to fight the COVID-19: Molecular docking,DFT calculations,ADME and td-Molecular dynamics simulations

In the present work, we have designed three molecules, acyclovir (A), ganciclovir (G) and derivative of hydroxymethyl derivative of ganciclovir (CH₂OH of G, that is D) and investigated their biological potential against the Mpro of nCoV via in silico studies. Further, density functional theory (DFT) calculations of A, G and D were performed using Gaussian 16 on applying B3LYP under default condition to collect the information for the delocalization of electron density in their optimized geometry. Authors have also calculated various energies including free energy of A, G and D in Hartree per particle. It can be seen that D has the least free energy. As mentioned, the molecular docking of the A, G and D against the Mpro of nCoV was performed using iGemdock, an acceptable computational tool and the interaction has been studied in the form of physical data, that is, binding energy for A, G and D were calculated in kcal/mol. It can be seen the D showed effective binding, that is, maximum inhibition that A and G. For a better understanding for the inhibition of the Mpro of nCoV by A, G and D, temperature dependent molecular dynamics simulations were performed. Different trajectories like RMSD, RMSF, Rg and hydrogen bond were extracted and analyzed. The results of molecular docking of A, G and D corroborate with the td-MD simulations and hypothesized that D could be a promising candidate to inhibit the activity of Mpro of nCoV.     

Synthesis and characterization of a novel polyazomethine ether for NLO application

Polymer containing azomethine and ether linking groups between phenylene rings has been prepared. It is a polycondensation reaction of a single monomer containing nitro as well as hydroxyl group in p,p^′ position from 4-nitroaniline and 4-hydroxy benzaldehyde. The polymer has been characterized by elemental analysis, IR, UV and NMR spectroscopies, viscometry and thermal studies. The thermotropic liquid crystalline behaviour of the polymer is investigated by optical polarizing microscopy. The crystalline behaviour of the polymer is confirmed by XRD study. The polymer shows good second harmonic generation for non-linear optical application.