Journal of the Iranian Chemical Society
Volume:3 Issue: 4, Dec 2006

In this review the fundamental question of how does protein-DNA or protein-RNA interactions affect the structures and dynamics of DNA, RNA, and protein is addressed. Two models of human serum albumin (HSA) bindings to calf-thymus DNA and transfer RNA (tRNA) are presented here. In these models the binding sites, stability and structural aspects of DNA-protein and RNA-protein are discussed. Electrostatic binding of DNA or RNA via backbone phosphate group to the positively charged amino acids on the surface of protein is prevailing. Two binding sites with K1 = 4.8 × 105 M-1 and K2 = 6.1 × 104 M-1 for protein-DNA and one binding affinity with K = 1.45 × 104 M-1 for protein-RNA are observed. A partial B to A-DNA transition is observed for protein-DNA complexes, while tRNA remains in A-family structure upon protein interaction.

The title compound, 1,2-dihydro-2,2,4-trimethylquinoline (TMQ), is a quinoline family member and is among others used to prevent the oxidative degradation of polymers. TMQ has been characterized by its fluorescence emission. In this work the effects of solvent, acidity, continuous irradiation and the influence of some interferents upon the fluorescence intensity of TMQ were investigated. Under the selected conditions (in propan-1-ol solution at λexcitation/λemission = 334 nm/412 nm), the fluorescence intensity is proportional to the concentration of TMQ over the range 0.05-5 µg ml-1 with a correlation coefficient of 0.9963. The proposed method was applied to the determination of TMQ in synthetic mixtures of polymer additives and specific rubber samples.

Several Schiff bases were synthesised from sulphonamide and resacetophenone. The characterisation was done by CHN analysis, IR and NMR spectral data. These Schiff bases were evaluated for their antimicrobial activity against both Gram-positive and Gram-negative bacteria as well as fungi. The antibacterial activity was studied against B. megaterium, E. coli, B. subtilis, P. fluorescens and antifungal activity against A. awamori. In addition, copper, nickel, cobalt, and iron complexes of two Schiff bases were also synthesised. Their structural characterisation was performed using CHN analysis and IR spectral data and their antibacterial and antifungal activities were also evaluated. The comparison of antimicrobial activities of the ligands and complexes shows that the presence of metal causes more inhibition i.e., more activity. Out of the four metals studied, cobalt and iron were found to have more antimicrobial activity.

Solid acids were developed and applied to the condensation reactions of indole with carbonyl compounds at ambient temperature. Tetra-(indolyl)methanes were obtained by the condensation reaction of indole with dialdehyde compounds.

compound bis(acetylacetonato)dichlorotin(IV) [Sn(acac)2Cl2] forms a distorted octahedral structure involving both oxygen atoms of the acetylacetone group. The two chlorides occupy the cis position, with Sn-Cl distances of Sn1-Cl1 = 2.380(2) Å, Sn1-O1 = 2.043(2) Å and Sn1-O2 = 2.093(2) Å. We report here a new and simple method for the synthesis of Sn(acac)2Cl2, its spectroscopic characterization and, for the first time, we report its crystal structure.

We have investigated different algorithms for the simulation of kinetics of small systems. We have simulated the first order reversible reaction with the Gillespie, Gibson and Bruck time simulation as a function of Poisson distribution and compared the results of three algorithms. We have also simulated intracellular viral kinetics for a genome with Gillespie and Poisson distribution algorithms.

Using upper consolute temperatures (UCT) and corresponding consolute compositions (CC) of water-phenol systems with each of 0.1 mol kg-1 salts and acids, 1.0% polyethylene glycol 200, 0.01 mol kg-1 surfactant and aromatic compounds, we obtained 0.01 mol kg-1 CaF2 and CrCl3 compositions. Focusing on UCT and CC, the role of valence electrons and shell number, basicity, hydrophilic, hydrophobic and π conjugated electrons of corresponding additives are reported. The surfactants and π conjugation electrons are noted to decrease the UCT in a constant ratio that depicts the state and inherent strength of ionic and molecular-water interactions. The data are useful in the investigation of cloud points of immiscible solutions based on the Hofmeister series.

Densities, ρ,viscosities, η, and refractive indices, nD, of glycine (Gly), DL-alanine (Ala), DL-valine (Val) (0.05, 0.10, 0.15, 0.20, 0.25 mol kg-1), and L-leucine (Leu) (0.02, 0.05, 0.10 mol kg-1) in water and in 0.20 mol kg-1 aqueous tetrapropylammonium bromide (TPAB) have been measured at 298.15, 303.15, 308.15, and 313.15 K. The density data have been utilized to calculate apparent molar volumes, Φv, partial molar volumes at infinite dilution, Φv°, and partial molar volumes of transfer, Φv°(tr) of amino acids. The viscosity data have been analyzed by means of Jones-Dole equation to obtain Falkenhagen coefficient, A, and Jones-Dole coefficient, B, free energy of activation of viscous flow per mole of solvent, Δµ1°*, and solute,Δµ2°*, and enthalpy, ΔH*, and entropy of activation, ΔS*, of viscous flow. The refractive index data have been used to calculate molar refractivity, RD, of amino acids in aqueous tetrapropylammonium bromide solutions. It has been observed that Φv°, B-coefficient and Δµ2°* vary linearly with increasing number of carbon atoms in the alkyl chain of amino acids, and they were split to get contributions from the zwitterionic end groups (NH3+, COO-) and methylene group (CH2) of the amino acids. The behavior of these parameters has been used to investigate the solute-solute and solute-solvent interactions as well as the effect of tetrapropylammonium cation (C3H7)4N+ on these interactions.

Eco-efficiency is critical for organisations that seek to be both environmentally conscious and profitable. It helps to "produce more out of less" to avoid wasting natural resources and to reduce emissions and damage to the environment. The textile coating and laminating industry, utilising solvent or water-based polymeric mixtures, is one of the industries coming under extreme environmental pressure to replace traditional procedures and use eco-efficient coating agents. In this study, eco-efficiency analysis was used to compare the eco-effectiveness of two different coating agents, polyacrylate and polyurethane, each in organic solution as well as aqueous dispersion forms. The "ecological fingerprint" and eco-efficiency portfolio were graphically illustrated for these coating agents based on the customer benefit, defined as coating one square meter of a textile fabric in a conventional laminating unit. According to the analysis results, polyacrylate dispersion in water was the most eco-efficient coating agent whilst polyurethane resin dissolved in organic solvent was found as the coating agent with the least acceptability as an eco-efficient product.

Some α-oxoketene-N,S- and N,N-acetals were selectively synthesized in good to excellent yields by the reaction of 1,1-dimethoxy-4,4-di(methylthio)-3-buten-2-one with primary and secondary amines under moderate conditions. Secondary amines in reaction with α-oxoketene dithioacetal yielded double-substitution products exclusively, whereas primary amines under the same conditions yielded the mono-substituted products as exclusive or main products.

N,N-disalicylidene-(R,S)(S,R)-1,2-ethanediamine crystallizes in orthorhombic space group Pbca with a = 9.5634(6), b = 14.2917(9), c = 16.9181(8) Å and Z = 4. The crystal structure was solved by direct methods and refined by full-matrix least squares to final values R1 = 0.0 + 399 and wR2 = 0.1004 with 2755 reflections (I > 2σ(I)). The N,N-disalicylidene-(R,S)(S,R)-1,2-ethanediamine molecules exhibit intramolecular N-H···O and are connected by C-H···O and C-H···π interactions to form a 2D supramolecular network.

Mononuclear complexes of Cu(II) have been prepared by reacting a 1:1:1 molar ratio of N- phOHA or N-phDHA, dipy or phen and cupric chloride where, N-phOHA = N-phenyl-O-hydroxyacetophenonimine, N-phDHA = N-phenyl-2,4-dihydroxy acetophenonimine, dipy = 2,2′-bipyridil, phen = 1,10-phenanthroline. All complexes were characterized on the basis of their microanalysis data, molar conductance, magnetic moment at room temperature, UV-Vis, IR, 1H NMR, and ESR spectra. The monomeric and ionic nature of complexes was confirmed by their magnetic moment data and molar conductance values. The ESR spectra of metal chelates in polycrystalline and solution state at 300 K and 77 K were recorded and their silent features are reported. The ESR spectra of the metal chelates provided information about their structure on the basis of Hamiltonian parameters of the complexes and also degree of covalency.

Kinetics and mechanism of oxidation of substituted and unsubstituted 4-oxoacids (S) by N-bromosuccinimide (NBS) in aqueous acetic acid medium have been studied potentiometrically. The reaction follows first-order kinetics, each in 4-oxoacids, NBS and H+. The effect of changes in the electronic nature of the substrate reveals that there is a development of positive charge in the transition state. Based on the kinetic results and the product analysis, a suitable mechanism has been proposed for the reaction of NBS with 4-oxoacids.