Jaturong PratuangdejkulWichit NosoongnoenGeorges Alexandre GuérinSylvan LoricMarc ContiJean Marie LaunayPhilippe ManivetE.A. 3621Hopital Lariboisiere AP-HPMahidol UniversityBioQuantaHopital Henri MondorHopital de Bicetre2018-08-202018-08-202006-03-21Chemical Physics Letters. Vol.420, No.4-6 (2006), 538-544000926142-s2.0-33644686042https://repository.li.mahidol.ac.th/handle/123456789/23174In the present work we used quantum mechanics calculations to predict the two pKa's of 5-hydrotryptamine (5-HT). Proton dissociation reaction succeeded to predict the experimental pKa1corresponding to ionization of the protonated amine group but failed for pKa2corresponding to ionization of the 5-hydroxyl group. For pKa2, a cluster-continuum model including three water molecules in the first hydration shell around 5-hydroxyl and 5-hydroxide groups enabled us to reproduce the experimental pKa2value. Furthermore, we demonstrated that specific conformations of acid/base pair of 5-HT is critical to predict accurately the experimental pKa's of the flexible 5-HT molecule. © 2006 Elsevier B.V. All rights reserved.Mahidol UniversityChemistryPhysics and AstronomyArticleSCOPUS10.1016/j.cplett.2006.01.035