Homology modeling and receptor-based 3D-QSAR study of carbonic anhydrase IX

Carbonic anhydrase (CA) IX is a very interesting subject for study due to its overexpression in cancer and its expression in very few normal tissues. There are not yet experimental 3D structures of the catalytic domain of this isozyme, and only a few computational studies have been reported. A homology model of CA IX was developed, and using Gold software 124 CA IX inhibitors were docked. The best poses of the ligands were then used as an alignment tool for the development of the first reported CA IX 3D-QSAR model. The obtained results confirm the reliability of the constructed CA IX model and the proposed computational strategy for investigating CAs.     

Limits of Multiplicities in Excellent Filtrations and Tensor Product Decompositions for Affine Kac-Moody Algebras

We express the multiplicities of the irreducible summands of certain tensor products of irreducible integrable modules for an affine Kac-Moody algebra over a simply laced Lie algebra as sums of multiplicities in appropriate excellent filtrations (Demazure flags). As an application, we obtain expressions for the outer multiplicities of tensor products of two fundamental modules for \(\widehat {\mathfrak {sl}}_{2}\) in terms of partitions with bounded parts, which subsequently lead to certain partition identities.     

Pd complexes of iminophosphine ligands: A homogeneous molecular catalyst for Suzuki–Miyaura cross-coupling reactions under mild conditions

The complexes formed by combining Pd(OAc)₂ and iminophosphine ligands (P^N) are active catalysts in Suzuki–Miyaura cross-coupling reactions under mild conditions. Aryl bromides and iodides, as well as benzyl chlorides give the corresponding coupled products in high yields at low temperatures (25–50 °C) using these catalysts. Iminophosphines containing the most sterically demanding groups attached to the N-imino moiety were the most effective ligands. New divalent Pd complexes of known iminophosphines were synthesised and their activity was compared with the in situ generated catalyst system. The complex resulting from the oxidative addition of 4-bromo anisole [Pd(4-CH₃OC₆H₄)Br(P^N)] was more active than the in situ generated system. However, palladacycles containing the iminophosphine ligand (e.g., {[C₆H₄CH(Me)₂St-Bu]Pd(P^N)}⁺PF₆⁻) were less active than the in situ generated catalyst due to the greater stability of the complexes that involve two bidentate ligands. Poisoning tests demonstrated that homogeneous mononuclear palladium species containing the iminophsophine ligand were responsible for the catalytic activity.     

Biosensor analysis for the kinetic study of polyphenols deterioration during the forced thermal oxidation of extra-virgin olive oil

The process of artificial rancidification of extra-virgin olive oil due to heating in an oxidizing atmosphere was studied by testing an actual kinetic model of the process and monitoring the thermal oxidative degradation of the polyphenols contained in it. To this end, a series of oxidative degradation experiments were carried out on extra-virgin olive oil samples under isothermal conditions at 98, 120, 140, 160, and 180 °C using a thermostatic silicon oil bath. The experimental procedure used in this study carefully followed the recommendations regarding the study of olive oil rancidification set out in the AOM procedure. The change in polyphenol concentration with time was monitored at selected temperatures using a tyrosinase biosensor operating in an organic phase (n-hexane). The activation energy for the polyphenol degradation process determined using the MacCallum method was found to be practically constant throughout most of the process.

Furthermore, the application of the so-called “model-fitting” method to this process enabled the specific constant rates to be determined at the above-mentioned selected temperatures. In addition, a confirmation of the activation energy value was obtained by the “model-fitting” method and the algorithm of the kinetic model equation best-fitting the experimental curve representing the whole process was checked.

Finally, further very interesting observations were made, for instance, the half-life concentration values of polyphenols at selected temperatures between 98 and 180 °C.