Sandbox Reserved 895: Difference between revisions
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Zhang and colleagues determined the binding interactions between RPE65 and emixustat by looking at the protein-ligand complex under three different considerations. The three considerations were RPE65 with a racemic emixustat, RPE65 with pure (''R'')-emixustat and RPE65 with pure (''S'')-emixustat. With all three cases, residual maps showed the presence of bound palmitate in the active site with the carboxylate oxygen forming a monodentate coordinate bond with the iron ion. The hydroxyl moiety in emixustat interacted via a hydrogen bond with the hydroxyl moiety in Thr147 whereas the primary amine was involved in a polar interaction with the carboxylate groups of Glu148 as well as the bound palmitate ligand. Crystal structure that was obtained in the presence of the racemic mixture of emixustat showed that the electron density was consistent with exclusive binding of the (''R'')-isomer ('''Figure 1B'''). Using the pure (''R'')-isomer and the pure (''S'')-isomer as a follow up study to the experiment confirmed the stereoselectivity for the (''R'')-isomer of emixustat. Stereoselectivity was present because of the interaction between the hydroxyl moieties in the enantiomers. Looking at the electron density of the 3-amino-1-phenylpropan-1-ol moiety of (''R'')-emixustat showed that when the racemic mixture was used the binding was that of the (''R'')-isomer. This showed that (''R'')-emixustat had a higher binding affinity when compared to (''S'')-emixustat. The difference in binding affinity and potency was likely because of the less favorable polar interaction observed in the (''S'')-isomer. Bond lengths for the hydroxyl-Thr137 Oγ , amine-Glu148 Oε2 and amine-palmitate O1 interactions were 3.1, 3.2 and 2.8 angstroms for the (''S'')-isomer and 3, 2.7 and 2.6 angstroms for the (''R'')-isomer respectively ('''Figure 8'''). | Zhang and colleagues determined the binding interactions between RPE65 and emixustat by looking at the protein-ligand complex under three different considerations. The three considerations were RPE65 with a racemic emixustat, RPE65 with pure (''R'')-emixustat and RPE65 with pure (''S'')-emixustat. With all three cases, residual maps showed the presence of bound palmitate in the active site with the carboxylate oxygen forming a monodentate coordinate bond with the iron ion. The hydroxyl moiety in emixustat interacted via a hydrogen bond with the hydroxyl moiety in Thr147 whereas the primary amine was involved in a polar interaction with the carboxylate groups of Glu148 as well as the bound palmitate ligand. Crystal structure that was obtained in the presence of the racemic mixture of emixustat showed that the electron density was consistent with exclusive binding of the (''R'')-isomer ('''Figure 1B'''). Using the pure (''R'')-isomer and the pure (''S'')-isomer as a follow up study to the experiment confirmed the stereoselectivity for the (''R'')-isomer of emixustat. Stereoselectivity was present because of the interaction between the hydroxyl moieties in the enantiomers. Looking at the electron density of the 3-amino-1-phenylpropan-1-ol moiety of (''R'')-emixustat showed that when the racemic mixture was used the binding was that of the (''R'')-isomer. This showed that (''R'')-emixustat had a higher binding affinity when compared to (''S'')-emixustat. The difference in binding affinity and potency was likely because of the less favorable polar interaction observed in the (''S'')-isomer. Bond lengths for the hydroxyl-Thr137 Oγ , amine-Glu148 Oε2 and amine-palmitate O1 interactions were 3.1, 3.2 and 2.8 angstroms for the (''S'')-isomer and 3, 2.7 and 2.6 angstroms for the (''R'')-isomer respectively ('''Figure 8'''). | ||
[[Media:RPE65_with_emixustat.mp4|Figure 8: 3-dimensional structure of (''R'')-emixustat bound in RPE65 with bond lengths ]] | |||
The difference in bond lengths also confirms the increase in binding affinity and potency of the (R)-isomer. These interactions can be seen in '''Figure 9''' . <ref> DOI 26075817 </ref> | The difference in bond lengths also confirms the increase in binding affinity and potency of the (R)-isomer. These interactions can be seen in '''Figure 9''' . <ref> DOI 26075817 </ref> | ||
