Esitetään Jyväskylän yliopiston matemaattis-luonnontieteellisen tiedekunnan suostumuksella julkisesti tarkastettavaksi yliopiston Ylistönrinteellä, salissa YAA303 tammikuun 24. päivänä 2014 kello 12.Academic dissertation to be publicly discussed, by permission of the Faculty of Mathematics and Science of the University of Jyväskylä, in Ylistönrinne, hall YAA303, on January 24, 2014 at 12 o'clock noon. Ligand-binding in a specific manner is vital to all cellular actions and can have a major effect on the activity and conformation of proteins. In addition to experimental techniques, computational methods, such as molecular dynamics (MD) simulations, have become an integral part in studies related to proteinligand interactions. The computational approach introduces a dynamic view of molecular interactions, and enables detailed structure-function studies. In addition, it may facilitate the estimation of binding affinities and help in identifying ligand-binding sites in proteins. In this thesis three pharmacologically important protein targets were studied with both computational and experimental methods: 1) ionotropic glutamate receptors (iGluRs), 2) filamin A (FLNa), and 3) T-cell protein tyrosine phosphatase (TCPTP). iGluRs mediate synaptic transmission in the nervous system and are linked to many neurological disorders. Partial agonism of the ligand binding domains (LBD) for these receptors was studied with MD simulations and the molecular mechanics generalised Born surface area (MM-GBSA) method. A previously unobserved intermediate closure stage for the GluN1 receptor subtype was identified, and new information about the closure mechanism was obtained. FLNa is an actin cross-linking protein linked to many cellular functions via its numerous binding partners. MM-GBSA calculations of binding free energy were shown to correlate well with the experimental data. Thus, ligands could be ranked based on their binding affinity, suggesting that also the rational design of FLNa-binding peptide mimetics would be conceivable. TCPTP is a ubiquitously expressed non-transmembrane phosphatase that negatively regulates many cancer-related kinases. TCPTP is normally autoinhibited, but several agonist molecules are known to activate it. Here, a putative binding site for TCPTP activators was identified and important structural determinants for novel activators were recognised. As TCPTP is not down-regulated in cancer cells, it is a promising target for tumor suppression.
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