Application of Online Multi-Internal Standard Calibration for Determination of Iodine by ICP-MS.

This study presents a comprehensive evaluation of the application of online multi-internal standard calibration (M.ISC) in determining iodine concentrations through inductively coupled plasma mass spectrometry (ICP-MS). Notably, M.

Gas-to-ionic liquid partition: QSPR modeling and mechanistic interpretation.

The present work was devoted to explore the quantitative structure-property relationships for gas-to-ionic liquid partition coefficients (log K ). A series of linear models were first established for the representative dataset (IL01). The optimal model was a four-parameter equation (1Ed) consisting of two electrostatic potential-based descriptors ( and V ), one 2D matrix-based descriptor (J_D/Dt) and dipole moment (μ).

QSPR study on Hydrophobicity of Pt(II) complexes with surface electrostatic potential-based descriptors.

Pt(II) complexes play an important role in bioinorganic chemistry due to their antitumor activities. In the present study, we focused on building predictive models for the hydrophobicity of Pt(II) complexes. A five-parameter model, integrating frontier orbital energies (E, E) and descriptors derived from electrostatic potentials on molecular surface, was firstly constructed by using multiple linear regression (MLR) method.

Prediction of the hydrophobicity of platinum(IV) complexes based on molecular surface properties.

A quantitative structure-property relationship (QSPR) study was performed for predicting the hydrophobicity of Pt(IV) complexes. Two four-parameter equations, one based solely on structural descriptors derived from electrostatic potentials (ESPs) on molecular surface, and the other integrated ESP descriptors with molecular surface area (A), were firstly constructed. Mechanistic interpretations of the structural descriptors introduced were elucidated in terms of solute-solvent intermolecular interactions.

The fate of heavy metals and salts during the wet treatment of municipal solid waste incineration bottom ash.

Bottom ash contains unfavorable contaminants that could leach into the circulating water used for wet treatment, and its improper disposal of bottom ash could cause ecological pollution. This study was to discuss the partition of heavy metals and salts of bottom ash into circulating water and ash stockpile runoff in wet treatment plants in southern China. The leachability of bottom ash before and after the wet treatment was also investigated.

Prediction on separation factor of chiral arylhydantoin compounds and recognition mechanism between chiral stationary phase and the enantiomers.

Chiral hydantoins display potential antidepressant and anticancer activities. The quantitative structure property relationship (QSPR) study on chiral compounds plays a key role in predicting the retention factor and the separation factor even the elution order of the enantiomers. In this study, the structures of chiral arylhydantoin compounds have been built to compute molecular structural parameters using VolSurf program.

Phosphorylation Mechanism of N-Acetyl-l-glutamate Kinase, a QM/MM Study.

In microorganisms and plants, N-acetyl-l-glutamate kinase (NAGK) catalyzes the second step in l-arginine synthesis, the phosphorylation of N-Acetyl-l-glutamate (NAG) to give N-acetyl-l-glutamate-5-phosphate. NAGK is only present in microorganisms and plants but absent in mammals, which makes it an attractive target for antimicrobial or biocidal development. Understanding the substrate binding mode and reaction mechanism of NAGK is crucial for targeting the kinase to develop potential therapies.

Phosphorylation Mechanism of Phosphomevalonate Kinase: Implications for Rational Engineering of Isoprenoid Biosynthetic Pathway Enzymes.

The mevalonate pathway is of important clinical, pharmaceutical, and biotechnological relevance. However, lack of the understanding of the phosphorylation mechanism of the kinases in this pathway has limited rationally engineering the kinases in industry. Here the phosphorylation reaction mechanism of a representative kinase in the mevalonate pathway, phosphomevalonate kinase, was studied by using molecular dynamics and hybrid QM/MM methods.

Interactions between pyrazole derived enantiomers and Chiralcel OJ: Prediction of enantiomer absolute configurations and elution order by molecular dynamics simulations.

The separation of enantiomers and confirmation of their absolute configurations is significant in the development of chiral drugs. The interactions between the enantiomers of chiral pyrazole derivative and polysaccharide-based chiral stationary phase cellulose tris(4-methylbenzoate) (Chiralcel OJ) in seven solvents and under different temperature were studied using molecular dynamics simulations. The results show that solvent effect has remarkable influence on the interactions.

Quantitative structure-hydrophobicity relationships of molecular fragments and beyond.

Quantitative structure-property relationship (QSPR) models were firstly established for the hydrophobic substituent constant (πX) using the theoretical descriptors derived solely from electrostatic potentials (EPSs) at the substituent atoms. The descriptors introduced are found to be related to hydrogen-bond basicity, hydrogen-bond acidity, cavity, or dipolarity/polarizability terms in linear solvation energy relationship, which endows the models good interpretability. The predictive capabilities of the models constructed were also verified by rigorous Monte Carlo cross-validation.

Identification of Peptide Inhibitors of Enveloped Viruses Using Support Vector Machine.

The peptides derived from envelope proteins have been shown to inhibit the protein-protein interactions in the virus membrane fusion process and thus have a great potential to be developed into effective antiviral therapies. There are three types of envelope proteins each exhibiting distinct structure folds. Although the exact fusion mechanism remains elusive, it was suggested that the three classes of viral fusion proteins share a similar mechanism of membrane fusion.

3D-QSAR and 3D-QSSR studies of thieno[2,3-d]pyrimidin-4-yl hydrazone analogues as CDK4 inhibitors by CoMFA analysis.

Aim: To investigate the structural basis underlying potency and selectivity of a series of novel analogues of thieno[2,3-d]pyrimidin-4-yl hydrazones as cyclin-dependent kinase 4 (CDK4) inhibitors and to use this information for drug design strategies.

Methods: Three-dimensional quantitative structure-activity relationship (3D-QSAR) and three-dimensional quantitative structure-selectivity relationship (3D-QSSR) models using comparative molecular field analysis (CoMFA) were conducted on a training set of 48 compounds. Partial least squares (PLS) analysis was employed.

Probing the chiral separation mechanism and the absolute configuration of malathion, malaoxon and isomalathion enantiomers by chiral high performance liquid chromatography coupled with chiral detector-binding energy computations.

Chiral separation mechanism determination and absolute configuration assignment are fundamental to the development of chiral stationary phases (CSPs) and the evaluation of both the enantioselective bioactivity and fate of chiral compounds. This work investigated the process of chiral separation and the assignment of the absolute configurations of malathion, malaoxon, and isomalathion using chiral high performance liquid chromatography (HPLC) coupled with chiral detector-binding energy computations. Hydrogen bonding was found to be a very important factor in the chiral separation of isomalathion on Chiralpak AD, although it did not exhibit a significant effect on the chiral separation of malathion and malaoxon on Chiralcel OJ.

Quantitative structure-chromatographic retention relationship for polycyclic aromatic sulfur heterocycles.

Polycyclic aromatic sulfur heterocycles (PASHs) are of concern in petroleum geochemistry and environmental chemistry. In the present study, geometrical optimization and electrostatic potential calculations have been performed for 114 PASHs reported previously at the HF/6-31G* level of theory. A group of 25 statistically based parameters have been extracted.

Ab initio study of the complexes of halogen-containing molecules RX (X=Cl, Br, and I) and NH3: towards understanding the nature of halogen bonding and the electron-accepting propensities of covalently bonded halogen atoms.

Ab initio calculations have been performed on a series of complexes formed between halogen-containing molecules and ammonia to gain a deeper insight into the nature of halogen bonding. It appears that the dihalogen molecules form the strongest halogen-bonded complexes with ammonia, followed by HOX; the charge-transfer-type contribution has been demonstrated to dominate the halogen bonding in these complexes. For the complexes involving carbon-bound halogen molecules, our calculations clearly indicate that electrostatic interactions are mainly responsible for their binding energies.

Binding interaction of gatifloxacin with bovine serum albumin.

The binding of gatifloxacin to bovine serum albumin (BSA) in aqueous solution was studied using fluorescence spectroscopy and absorbance spectra, Further, the interactions influenced by Fe3+ and Cu2+ were also explored in this work. Based on Scatchard's site-binding model and florescence quenching, practical formulas for small molecule ligands to bio-macromolecules have been proposed. The binding parameters were measured according to suggested models, and the binding distance and the transfer efficiency of energy between gatifloxacin and BSA were also obtained in view of the Förster theory of non-radiation energy transfer.