Termodinamičko i strukturno istraživanje kompleksiranja homociklopeptida s halogenidnim i oksoanionima u acetonitrilu i dimetilsulfoksidu

master's thesis

• Title (english): Thermodynamic and structural studies of the complexation of homocyclopeptides with halide and oxoanions in acetonitrile and dimethylsulfoxide
• Author: Siniša Tarana
• Mentor: Gordan Horvat (mentor)
• Committee member: Gordan Horvat (predsjednik povjerenstva)
• Committee member: Vladimir Stilinović (član povjerenstva)
• Committee member: Aleksandra Maršavelski (član povjerenstva)
• Committee member: Branimir Bertoša (član povjerenstva)
• Granter: University of Zagreb; Faculty of Science; (Department of Chemistry); Zagreb
• Defense date and country: 2018-11-08, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Chemistry

Abstract

U okviru ovog rada istražen je kompleksacijski afinitet tri derivata cikličkih peptida prema halogenim, tiocijanatnim i oksoanionima u acetonitrilu i dimetilsulfoksidu (DMSO). Ligand L1 je pentaleucinski derivat ciklopeptida. Druga dva liganda su izgrađena od lizinskih podjedinica povezanih u prsten pri čemu su amino skupine bočnih lanaca zaštićene tert-butilkarbonilnom (BOC) skupinom pri čemu receptor L2 sadržava četiri takve podjedinice dok je ligand L3 sastavljen od pet podjedinica. Konstante stabilnosti liganada L1, L2 i L3 s proučavanim anionima određene su mikrokalorimetrijskim i 1H NMR titracijama. Određene su konstante stabilnosti odgovarajućih kompleksa, kao i pripadajuće termodinamičke reakcijske veličine. Da bi se stekao detaljniji uvid u procese vezanja kationa i molekula otapala s istraživanim spojevima provedene su odgovarajuće računalne simulacije primjenom metode klasične molekulske dinamike.
Proučeni ciklopeptidni ligandi bolje vežu anione u acetonitrilu u usporedbi s dimetilsulfoksidom. Uočeno je da je stabilnost anionskih kompleksa pentamernih derivata L2 i L3 u DMSO-u veća od pripadajućih kompleksa s tetramernim derivatom L1. Rezulutati 1H NMR titracija i simulacija molekulske dinamike upućuju na to da su ioni vezani pomoću amidnih skupina ciklopeptida. Također, u slučaju kompleksa liganada L1 i L2 s ionom H2PO42– opaženo je da u koordinaciji iona uz amidne protone sudjeluju i karbamatni protoni.

Abstract (english)

Complexation affinities of the three cyclopeptide derivatives for halogen, thiocyanate and oxoanions were studied in acetonitrile and dimethylsulfoxide (DMSO). Ligand L1 was a pentaleucine cyclopeptide derivative. Other two cyclopeptidic ligands were comprised of lysine subunits protected by tert-butylcarbonyl (BOC) group. Ligand L2 was built out of four such subunits while ligand L3 contained five of them. Stability constants of L1, L2 and L3 complexes with studied anions were determined by means of microcalorimetric and 1H NMR titrations. To get more detailed insight into the binding of anions by the investigated cyclopeptide derivatives, classical molecular dynamics simulations were carried out.
Investigated cyclopeptide ligands showed larger affinity for all anions in acetonitrile than in dimethylsulfoxide. It was found that the stability of the anion complexes of pentameric ligands L2 and L3 was higher than that corresponding to the tetrameric ligand L1. The results of 1H NMR titrations and of molecular dynamics simulations indicate that the bound anions were coordinated by the amide groups of cyclopeptide ligands. In the case of L1 and L2 complexes with H2PO4– anion the participation of carbamate protons in the anion coordination was observed.

• Keywords: ciklopeptidi; anioni; kompleksiranje; kalorimetrija; 1H NMR; molekulska dinamika
• Keywords (english): cyclopeptides; anions; complexation; calorimetry; 1H NMR; molecular dynamics
• Language: croatian
• URN:NBN: urn:nbn:hr:217:188894
• Study programme: Title: Graduate university studies in chemistry; specializations in: Research programme; Course: Research programme; Study programme type: university; Study level: graduate; Academic / professional title: magistar/magistra kemije (magistar/magistra kemije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access; Embargo expiration date: 2020-11-08
• Created on: 2018-11-26 11:50:38