Solution- and bound-state conformational study of N,N',N"-triacetyl chitotriose and other analogous potential inhibitors of hevamine: application of trNOESY and STD NMR spectroscopy.
The solution-state conformations of N,N',N"-triacetyl chitotriose (1) and other potential chitinase inhibitors 2-4 were studied using a combination of NMR spectroscopy (NOESY) and molecular mechanics calculations. Determination solely of the global energy minimum conformation was found to be insufficient for an agreement with the NMR results. An appropriate consistency between the NMR experimental data and theoretical calculations was only reached by assessing the structures as population-weighted average conformers based on Boltzmann distributions derived from the calculated relative energies. Analogies, but also particular differences, between the synthetic compounds 2-4 and the naturally-occurring N,N',N"-triacetyl chitotriose were found. Furthermore, the conformation of compounds 1 and 2 when bound to hevamine was also studied using transferred NOESY experiments and the binding process was found to impart a level of conformational restriction on the ligands. The preferred conformation as determined for 1 in the bound state to hevamine belonged to one of the conformational families found for the compound when free in solution, although full characterisation of the bound-state conformations was impeded due to severe signal overlap. Saturation transfer difference NMR experiments were also employed to analyse the binding epitopes of the bound compounds. We thus determined that it is mainly the acetyl amido groups of the trisaccharide and the heterocyclic moiety which are in close contact with hevamine.
Institut für Organische Chemie und Strukturanalytik, Universität Potsdam, Am Neuen Palais 10, 14415 Potsdam, Germany.
Antje
A
Germer
Clemens
C
Mügge
Martin G
MG
Peter
Antje
A
Rottmann
Erich
E
Kleinpeter
D002240:Carbohydrate Sequence; D055598:Chemical Phenomena; D002627:Chemistry, Physical; D002688:Chitinases / Q000037:antagonists & inhibitors*; D004791:Enzyme Inhibitors / Q000737:chemistry* / Q000494:pharmacology; D000939:Epitopes / Q000737:chemistry; D006027:Glycosides / Q000737:chemistry; D028482:Hevea / Q000737:chemistry; D006859:Hydrogen / Q000737:chemistry; D009682:Magnetic Resonance Spectroscopy; D008958:Models, Molecular; D008968:Molecular Conformation; D009113:Muramidase / Q000037:antagonists & inhibitors*; D010940:Plant Proteins; D011485:Protein Binding; D014312:Trisaccharides / Q000737:chemistry* / Q000494:pharmacology
D004791:Enzyme Inhibitors; D000939:Epitopes; D006027:Glycosides; D010940:Plant Proteins; D014312:Trisaccharides; C019117:N,N',N''-triacetylchitotriose; D006859:Hydrogen; D002688:Chitinases; C063764:hevamine; D009113:Muramidase