The druggability of the ATP binding site of glycogen phosphorylase kinase probed by coumarin analogues

Glycogen phosphorylase kinase (PhK) converts by phosphorylation, the inactive glycogen phosphorylase (GPb) into active GPa in the glycogenolytic pathway. It is a complex enzyme comprising of the catalytic (γ) and three regulatory subunits (α, β, δ) forming a hexadecamer with stoichiometry (αβγδ)4. Several studies have indicated PhK as a promising target for the development of antihyperglycemics as its inhibition blocks glycogenolysis in liver and a potential therapeutic target for cancer against pathological angiogenesis and tumor progression. The identification of compounds that inhibit the kinase through their direct binding to its catalytic site is an effective approach to identify bioactive molecules of therapeutic significance. Towards this, the structure of the N-terminal kinase domain (residues 1–298) of the catalytic γ subunit of PhK (PhKγtrnc) has been determined by X-ray crystallography while staurosporine and indirubin analogues have been characterized as potent inhibitors targeting the ATP binding site. In this study, a series of 38 synthetic analogues of naturally occurring coumarins were screened for inhibition of PhKγtrnc, in vitro, using a photometric assay. The IC50 values of the two most potent compounds were determined for PhKγtrnc and the pharmacologically relevant target, human liver isoform (PHKG2A). Their cellular efficacy and toxicity in HepG2 cells were further assessed ex vivo. Docking experiments and the structural comparison with previously described inhibitors reveal the binding mode of the coumarin scaffold at a no hinge region of the ATP site of PhK and the role of a conserved β3-Lys in binding. The experimental findings provide structural insights with implications to the kinase targeting and drug design

Strong Binding of C-Glycosylic1,2-Thiodisaccharides to Galectin-3─Enthalpy-Driven Affinity Enhancement by Water-Mediated Hydrogen Bonds

Galectin-3 is involved in multiple pathways of many diseases, including cancer, fibrosis, and diabetes, and it is a validated pharmaceutical target for the development of novel therapeutic agents to address unmet medical needs. Novel 1,2-thiodisaccharides with a C-glycosylic functionality were synthesized by the photoinitiated thiol-ene click reaction of O-peracylated 1-C-substituted glycals and 1-thio-glycopyranoses. Subsequent global deprotection yielded test compounds, which were studied for their binding to human galectin-3 by fluorescence polarization and isothermal titration calorimetry to show low micromolar K d values. The best inhibitor displayed a K d value of 8.0 μM. An analysis of the thermodynamic binding parameters revealed that the binding Gibbs free energy (Δ G) of the new inhibitors was dominated by enthalpy (Δ H). The binding mode of the four most efficient 1,2-thiodisaccharides was also studied by X-ray crystallography that uncovered the unique role of water-mediated hydrogen bonds in conferring enthalpy-driven affinity enhancement for the new inhibitors. This 1,2-thiodisaccharide-type scaffold represents a new lead for galectin-3 inhibitor discovery and offers several possibilities for further development

La Academia : revista de cultura hispano portuguesa, latino-Americana: Tomo II Número 20 - 1877 diciembre 7

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

La mañana : diario político: Año VI Número 1671 - 1881 julio 28

Copia digital. Madrid : Ministerio de Cultura. Subdirección General de Coordinación Bibliotecaria, 200

High Consistency of Structure-Based Design and X-Ray Crystallography: Design, Synthesis, Kinetic Evaluation and Crystallographic Binding Mode Determination of Biphenyl-<i>N</i>-acyl-β-<span style="font-variant: small-caps">d</span>-Glucopyranosylamines as Glycogen Phosphorylase Inhibitors

Structure-based design and synthesis of two biphenyl-N-acyl-&#946;-d-glucopyranosylamine derivatives as well as their assessment as inhibitors of human liver glycogen phosphorylase (hlGPa, a pharmaceutical target for type 2 diabetes) is presented. X-ray crystallography revealed the importance of structural water molecules and that the inhibitory efficacy correlates with the degree of disturbance caused by the inhibitor binding to a loop crucial for the catalytic mechanism. The in silico-derived models of the binding mode generated during the design process corresponded very well with the crystallographic data

Affinity Crystallography Reveals Binding of Pomegranate Juice Anthocyanins at the Inhibitor Site of Glycogen Phosphorylase: The Contribution of a Sugar Moiety to Potency and Its Implications to the Binding Mode

Anthocyanins (ACNs) are dietary phytochemicals with an acknowledged therapeutic significance. Pomegranate juice (PJ) is a rich source of ACNs with potential applications in nutraceutical development. Glycogen phosphorylase (GP) catalyzes the first step of glycogenolysis and is a molecular target for the development of antihyperglycemics. The inhibitory potential of the ACN fraction of PJ is assessed through a combination of in vitro assays, ex vivo investigation in hepatic cells, and X-ray crystallography studies. The ACN extract potently inhibits muscle and liver isoforms of GP. Affinity crystallography reveals the structural basis of inhibition through the binding of pelargonidin-3-O-glucoside at the GP inhibitor site. The glucopyranose moiety is revealed as a major determinant of potency as it promotes a structural binding mode different from that observed for other flavonoids. This inhibitory effect of the ACN scaffold and its binding mode at the GP inhibitor binding site may have significant implications for future structure-based drug design endeavors

Affinity Crystallography Reveals Binding of Pomegranate Juice Anthocyanins at the Inhibitor Site of Glycogen Phosphorylase: The Contribution of a Sugar Moiety to Potency and Its Implications to the Binding Mode

Anthocyanins (ACNs) are dietary phytochemicals with an acknowledged therapeutic significance. Pomegranate juice (PJ) is a rich source of ACNs with potential applications in nutraceutical development. Glycogen phosphorylase (GP) catalyzes the first step of glycogenolysis and is a molecular target for the development of antihyperglycemics. The inhibitory potential of the ACN fraction of PJ is assessed through a combination of in vitro assays, ex vivo investigation in hepatic cells, and X-ray crystallography studies. The ACN extract potently inhibits muscle and liver isoforms of GP. Affinity crystallography reveals the structural basis of inhibition through the binding of pelargonidin-3-O-glucoside at the GP inhibitor site. The glucopyranose moiety is revealed as a major determinant of potency as it promotes a structural binding mode different from that observed for other flavonoids. This inhibitory effect of the ACN scaffold and its binding mode at the GP inhibitor binding site may have significant implications for future structure-based drug design endeavors

Agroecosystems shape population genetic structure of the greenhouse whitefly in Northern and Southern Europe

Background: To predict further invasions of pests it is important to understand what factors contribute to the genetic structure of their populations. Cosmopolitan pest species are ideal for studying how different agroecosystems affect population genetic structure within a species at different climatic extremes. We undertook the first population genetic study of the greenhouse whitefly (Trialeurodes vaporariorum), a cosmopolitan invasive herbivore, and examined the genetic structure of this species in Northern and Southern Europe. In Finland, cold temperatures limit whiteflies to greenhouses and prevent them from overwintering in nature, and in Greece, milder temperatures allow whiteflies to inhabit both fields and greenhouses year round, providing a greater potential for connectivity among populations. Using nine microsatellite markers, we genotyped 1274 T. vaporariorum females collected from 18 greenhouses in Finland and eight greenhouses as well as eight fields in Greece. Results: Populations from Finland were less diverse than those from Greece, suggesting that Greek populations are larger and subjected to fewer bottlenecks. Moreover, there was significant population genetic structure in both countries that was explained by different factors. Habitat (field vs. greenhouse) together with longitude explained genetic structure in Greece, whereas in Finland, genetic structure was explained by host plant species. Furthermore, there was no temporal genetic structure among populations in Finland, suggesting that year-round populations are able to persist in greenhouses. Conclusions: Taken together our results show that greenhouse agroecosystems can limit gene flow among populations in both climate zones. Fragmented populations in greenhouses could allow for efficient pest management. However, pest persistence in both climate zones, coupled with increasing opportunities for naturalization in temperate latitudes due to climate change, highlight challenges for the management of cosmopolitan pests in Northern and Southern Europe