Synthesis of Castor Oil-Based Quaternary Ammonium Salt and Modification of Attapulgite for Treating Industrial Wastewaters.

In order to develop multifunctional quaternary ammonium salts and explore their advantages as modifiers for wastewater treatment, castor oil-based quaternary ammonium salts were synthesised and subsequently used as modifiers for attapulgite treatment. The structures of untreated and treated attapulgite were compared by Fourier transform infrared spectra and X-ray diffraction. The mechanism of modification was speculated.

Optimization of Ultrasonic-Microwave Synergistic Extraction of Ricinine from Castor Cake by Response Surface Methodology.

Castor cake is the residue in castor oil production in which many active components exist and the major one among them is ricinine. In this study, optimization of extraction of ricinine from castor cake using ultrasonic-microwave synergistic extraction (UMSE) was investigated to obtain high yield and purity by Box-Behnken design (BBD) response surface design. The optimal conditions of extraction were: ultrasound power 342 W, extracting time 5 min, microwave power 395 W, and non-significant factor of liquid/solid ratio 1:10.

Improving the neutral phytase activity from Bacillus amyloliquefaciens DSM 1061 by site-directed mutagenesis.

Neutral phytase is used as a feed additive for degradation of anti-nutritional phytate in aquatic feed industry. Site-directed mutagenesis of Bacillus amyloliquefaciens DSM 1061 phytase was performed with an aim to increase its activity. Mutation residues were chosen based on multiple sequence alignments and structure analysis of neutral phytsaes from different microorganisms.

Utilization of halogen bond in lead optimization: a case study of rational design of potent phosphodiesterase type 5 (PDE5) inhibitors.

For proof-of-concept of halogen bonding in drug design, a series of halogenated compounds were designed based on a lead structure as new inhibitors of phosphodiesterase type 5. Bioassay results revealed a good correlation between the measured bioactivity and the calculated halogen bond energy. Our X-ray crystal structures verified the existence of the predicted halogen bonds, demonstrating that the halogen bond is an applicable tool in drug design and should be routinely considered in lead optimization.

Molecular dynamics simulations on the mechanism of transporting methylamine and ammonia by ammonium transporter AmtB.

AmtB is one of the ammonium transporter proteins facilitating the ammonium transport across the cellular membranes. Experimentally, the substrate used in in vitro studies is the radio labeled [(14)C]methylammonium, rather than ammonium itself. To explore the similarity and difference of the conduction mechanism of methylamine and ammonia molecules through AmtB, molecular dynamics simulations on 22 carefully designed systems were performed, which demonstrated that methylamine could be automatically transported in a very similar way to ammonia.

C-X...H contacts in biomolecular systems: how they contribute to protein-ligand binding affinity.

The hydrogen bond acceptor capability of halogens has long been underappreciated in the field of biology. In this work, we have surveyed structures of protein complexes with halogenated ligands to characterize geometrical preferences of C-X..

Halogen bonding--a novel interaction for rational drug design?

Although recognized in small molecules for quite some time, the implications of halogen bonding in biomolecular systems are only now coming to light. In this study, several systems of proteins in complex with halogenated ligands have been investigated by using a two-layer QM/MM ONIOM methodology. In all cases, the halogen-oxygen distances are shown to be much less than the van der Waals radius sums.

Brain-specific regulator of G-protein signaling 9-2 selectively interacts with alpha-actinin-2 to regulate calcium-dependent inactivation of NMDA receptors.

Regulator of G-protein signaling 9-1 (RGS9-1) and RGS9-2 are highly related RGS proteins with distinctive C termini arising from alternative splicing of RGS9 gene transcripts. RGS9-1 is expressed in photoreceptors where it functions as a regulator of transducin. In contrast, RGS9-2 is abundantly expressed in the brain, especially in basal ganglia, where its specific function remains poorly understood.