2.4.1.133 | more |
synthesis of xyloside analogues with substitution of the endocyclic oxygen atom by sulfur or carbon and investigation of them as substrates for beta-1,4-galactosyltransferase 7 (beta4GalT7), overview. The analogues with an endocyclic sulfur atom prove to be excellent substrates for b4GalT7, and are galactosylated approx. fifteen times more efficiently than the corresponding xyloside. The 5a-carba-beta-xylopyranoside in the D-configuration proves to be a good substrate for beta4GalT7, whereas the enantiomer in the L-configuration shows no activity. X-ray crystallography, NMR spectroscopy, and molecular modeling provide a rationale for the pronounced activity of the sulfur analogues. Favorable Pi-Pi interactions between the 2-naphthyl moiety and a tyrosine side chain of the enzyme are observed for the thio analogues (1S,2R,3S,4S)-4-(2-naphthyloxy)cyclohexan-1,2,3-triol, 4-ethyl-6-([(1R,2R,3S,4R)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one, and 4-ethyl-6-([(1S,2S,3R,4S)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one. The carbaxyloside of iliparcil are synthesized as well as its L-xylo-enantiomers 4-ethyl-6-([(1R,2R,3S,4R)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one and 4-ethyl-6-([(1S,2S,3R,4S)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one. The L-xylo-derivative 4-ethyl-6-([(1S,2S,3R,4S)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one shows a much higher antithrombotic activity compared to the D-xylo-enantiomer 4-ethyl-6-([(1R,2R,3S,4R)-2,3,4-trihydroxycyclohexyl]oxy)-2H-1-benzopyran-2-one and only the compound with L-xylo conformation functions as substrate for beta4GalT7 when assayed with enzyme extracts from chicken embryo. This is in stark contrast to other investigations where L-enantiomers of xylosides rarely act as substrates for beta4GalT7. Quantum mechanical calculations and docking simulations, overview |
Homo sapiens |
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