ABCC2 is a transporter with key influence on liver and kidney pharmacokinetics. In order to explore the structure–activity relationships of compounds that modulate ABCC2, and by doing so gain insights into drug–drug interactions, we screened a library of 432 compounds for modulators of radiolabeled β-estradiol 17-(β-D-glucuronide) (EG) and fluorescent 2′,7′-dichlorofluorescin transport (CDCF) in membrane vesicles. Following the primary screen at 80 μM, dose–response curves were used to investigate in detail 86 compounds, identifying 16 low μM inhibitors and providing data about the structure–activity relationships in four series containing 19, 24, 10, and eight analogues. Measurements with the CDCF probe were consistently more robust than for the EG probe. Only one compound was clearly probe-selective with 50-fold difference in the IC50s obtained by the two assays. We built 24 classification models using the SVM and fused-XY Kohonen methods, revealing molecular descriptors related to number of rings, solubility and lipophilicity as important to distinguish inhibitors from inactive compounds. This study is to our best knowledge the first to provide details about structure–activity relationships in ABCC2 modulation.

Protein stability provides advantageous development of novel properties and can be crucial in affording tolerance to mutations that introduce functionally preferential phenotypes. Consequently, understanding the determining factors for protein stability is important for the study of structure-function relationship and design of novel protein functions. Thermal stability has been extensively studied in connection with practical application of biocatalysts. However, little work has been done to explore the mechanism of pH-dependent inactivation. In this study, bioinformatic analysis of the Ntn-hydrolase superfamily was performed to identify functionally important subfamily-specific positions in protein structures. Furthermore, the involvement of these positions in pH-induced inactivation was studied. The conformational mobility of penicillin acylase in Escherichia coli was analyzed through molecular modeling in neutral and alkaline conditions. Two functionally important subfamily-specific residues, Gluβ482 and Aspβ484, were found. Ionization of these residues at alkaline pH promoted the collapse of a buried network of stabilizing interactions that consequently disrupted the functional protein conformation. The subfamily-specific position Aspβ484 was selected as a hotspot for mutation to engineer enzyme variant tolerant to alkaline medium. The corresponding Dβ484N mutant was produced and showed 9-fold increase in stability at alkaline conditions. Bioinformatic analysis of subfamily-specific positions can be further explored to study mechanisms of protein inactivation and to design more stable variants for the engineering of homologous Ntn-hydrolases with improved catalytic properties.

Multidrug resistance associated protein 2 (MRP2/ABCC2) is a membrane transport protein that can potentially affect the disposition of many substrate drugs and their metabolites. Recently, we studied the interaction of a library of 432 compounds with ABCC2, and the structure-activity relationship (SAR) of a subset of 64 compounds divided into four scaffolds (Wissel, G. et al., 2015. Bioorg Med Chem., 23(13), pp.3513–25). We have now expanded this test set by investigating 114 new compounds, of which 71 are representative of the previous four scaffolds and 43 compounds belong to a new scaffold. Interaction with ABCC2 was assessed by measuring the compounds effect on 5(6)-carboxy-2′,7′-dichlorofluorescein transport in the vesicular transport assay. In line with our previous study, we observed that anionic charge is not essential for inhibition of ABCC2 transport, even though it often increases the inhibitory activity within the analogue series. Additionally, we found that halogen substitutions often increase the inhibitory activity. The results confirm the importance of structural features such as aromaticity and lipophilicity for ABCC2 inhibitory activity.

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ExtEndEd AbstrAct:The paper addresses the issues of alkoxide method of sol-gel synthesis and non-hydrolytic method of sol-gel synthesis and colloidal method of sol-gel synthesis. The authors also consider an alternative approach based on the use of soluble silicates as precursors in the sol-gel technology, of nanocomposites. It was shown that nanocomposites can be produced through aerogels. The paper also analyzes the mixing technologies of nanocomposites preparation. It has been demonstrated the possibility to change the types of nano-phase which is used for obtaining nanocomposites in different approaches. Various models of packaging spherical, fibrous and layered nanoparticles, introduced into the structure of the nanocomposite, in the preparation thereof were examined.Key words: Nanocomposites, sol-gel synthesis, soluble silicates, metal alkoxide, sols, gels, aerogels, packing of spherical nanoparticles, packing of fibrous nanoparticles. THE RESULTS OF THE SPECIALISTS' AND SCIENTISTS' RESEARCHES MAchinE-rEAdAblE inforMAtion on cc-licEnsEs (htMl-codE) in MEtAdAtA of thE pApEr Mixing technologies of nanocompositesA method for producing polymer nanocomposites in the melt, so-called extrusion method, consists in mixing the molten polymer with nanosized material particles, surface modified with organic compounds. During the intercalation, the polymer chains substantially change their shape and lose conformational entropy. As the driving force of this process is likely when mixed, the most significant contribution is made, the enthalpy of interaction in the system, the polymer -nanoscale filler. It should be added, for example, that the polymer nanocomposites based on clay materials is successfully produced by means of extrusion [104, 107]. The advantage of an extrusion method is the absence of any solvents, which eliminates the presence of hazardous effluents, the process rate considerably higher and technological design of manufacture considerably easier. That is, for the preparation of polymer nanocomposites in industrial-scale extrusion method is the most preferred, less costly raw material and maintenance of the technological scheme.The polymer-silicate nanocomposite silicate modified with organic substances, in obtaining, swells in a solvent such as toluene or N-dimethylformamide. Then, it is added to the polymer solution which penetrates into the interlayer space of the silicate. Then, solvent removal is carried out by vacuum evaporation. The main advantage of this method consists in that the «polymer-layered silicate» can be obtained based on a polymer of low polarity or non-polar material. Nevertheless, this method is not widely used in industry due to the high solvent consumption [105]. By using mixing technologies, an important factor is the viscosity and fluidity of the reaction mixture. This is especially important for highly filled compositions, where low binder content, that is in the liquid phase. In industrial practice, a relatively long known way to increase mobility and moldability of the compo...