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Browsing by Subject "11β-Hydroksisteroididehydrogenaasientsyymit 1 ja 2"

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  • Vuorinen, Anna (2010)
    11β-hydroxysteroid dehydrogenase/reductase (11β-HSD) enzymes 1 and 2 regulate the amount of cortisone and cortisol in human tissues. Since overexpression of 11β-HSD1 especially in the adipose tissue causes symptoms of metabolic syndrome, selective inhibition of 11β-HSD1 provides a way to treat this syndrome and type II diabetes. Inhibition of 11β-HSD2 causes cortisol-dependent mineralocorticoid activation, which leads to hypertensive side effects. There are several reported 11β-HSD1 inhibitors, for selective 11β-HSD2 inhibitition, only a few compounds have been developed. The difference between 11β-HSD1 and 2 ligand binding sites is unknown, which complicates the search of selective inhibitors to both of the enzymes. This study was done with two aims: (1) to identify the difference between the two isozymes, (2) to create pharmacophore models for selective 11β-HSD2 inhibitiors. These tasks were approached with computational methods: homology modeling, docking, ligand-based pharmacophore modeling and virtual screening. The homology model of 11β-HSD2 was constructed using SwissModeler and it showed satisfying superimposition both with is template 17β-HSD1 and 11β-HSD1. The difference between the enzymes could not be identified by visual inspections Therefore, seven compounds, of which six are 11β-HSD2 -selective, were docked both to 11β-HSD1 and 11β-HSD2 ligand binding sites using the program GOLD. The docking results revealed that the compounds orientate differently in the enzymes. To 11β-HSD1, the compounds were anchored similar than unselective compound carbenoxolone, whereas in 11β-HDS2, they adopted a flipped binding mode. The flipped binding mode in 11β-HDS2 enables hydrogen bonds to Ser310 and to Asn171, both residues that are only present in 11β-HSD2. Pharmacophore modeling and virtual screening were done using the program LigandScout3.0. The ligand-based pharmacophores were based on the six 11β-HSD2 selective compounds, which were also used for the docking studies. Both of the models consisted of six features (hydrogen bond acceptors, hydrogen bond donor and hydrophobic feature) besides the exclusion volumes. The most important features considering the 11β-HSD2 selectivity seem to be the hydrogen bond acceptor feature that could interact with the Ser310 and the hydrogen bond donor feature next to it. The interaction pair for this hydrogen bond donor feature was not observed in the homology model. However, a possibility of water molecule as an interaction pair was evaluated and it seems to be a possible solution to the problem. Since both of the models were able to find the selective 11β-HSD2 inhibitors and exclude the unselective ones from the test set database, they were employed for the screening of the database that consists of 2700 compounds stored at the University of Innsbruck. From the hits of these screenings ten compounds were selected and sent to biological testing. The results of the biological tests will decide how well the models represent the theory of the 11β-HSD2 selectivity.