Xanthene-based artifical enzymes and a dimeric calixpyrrole as a chromogenic chemosensor

Şaki, Neslihan
This thesis covers the combination of two seperate work accomplished during the throughout the study. In the first part of the study, xanthene based artificial enzymes were synthesized, and kinetic hydrolysis studies done. Artificial enzyme design is an active field of supramolecular chemistry and metalloenzymes are attractive targets in such studies. Enzymatic catalysis is essentially a ءmultifuctional̕ catalysis. As part of our work, we designed and synthesized three novel xanthene derivatives. All three model contain Zn(II) in their active sites. Using the model substrate p-nitrophenyl acetate, we showed that the bifunctional model is at least an order of magnitude more active in catalyzing the hydrolysis of the substrate. Compared to the uncatalyzed hydrolysis reaction of the p-nitrophenyl ester at pH 7.0, the bifunctional model complex showed a 5714-fold rate acceleration. The second part of the thesis involves the design of a dimeric calixpyrrole as a chromogenic chemosensor. Anions are involved in a large number of biological processes and there is an interest in developing molecular sensors for these charged species. The calixpyrroles are a class of old but new heterocalixarene analogues that show considerable promise in the area of anion sensing. In this work, we have designed, synthesized and characterized a calixpyrrole-dimer anion sensor for its anion binding strength. The dimer forms stable complexes with p-nitrophenolate ion. This formed complex is used as a colorimetric sensor by displacing the chromogenic anion with the addition of various anions. like fluoride and acetate. The receptor shows strong affinity and high selectivity for fluoride anion, and also show reasonable affinity toward acetate. Thus, effective optical sensing of biochemically relevant these anions is accomplished using the calixpyrrole dimer.


IMAMOGLU, EO; İmamoğlu, Vacit (1992-03-01)
Based on the findings of a cross-cultural study, this paper aims (a) to explore changes in the current life situations and attitudes of the Turkish elderly toward institutional living in terms of age, sex, and urbanization; and (b) by way of comparison with the Swedish case, to assess the generalizability of the findings within a cross-cultural perspective. Indepth interviews were carried out with 448 Turkish males and females (55-71 years) residing in small towns, cities, and metropolitan areas. The comp...
Unexpected cyclization of dipyrilydl-glycoluril in the presence of formaldehyde and strong acid : a new scaffold with a potential as a receptor and synthesis of vairous calixarene precursors
Cevheroğlu, Orkun; Akkaya, Engin Umut; Department of Chemistry (2005)
This thesis covers combination of two independent works accomplished throughout the study. One part research is about the unexpected cyclization of Dipyridyl-glycoluril, and the other part is about synthesis of precursor calix[4]arene derivatives. In an attempted synthesis of peripherally pyridine substituted cucurbituril, an unexpected cyclized product was obtained. A careful NMR analysis followed by mass spectrometry and preliminary crystallographic analyses, helped us in resolving the structure. The stru...
KOCABIVIK, S; PERLIN, MH (Elsevier BV, 1994-01-01)
1. Oligonucleotide-directed mutagenesis of APH(3')-II was used to investigate the functions of key amino acids in the P-loop analogous motif of the enzyme. 2. The mutations of Gly205 --> GIu, Gly210 --> Ala and Arg211 --> Pro considerably reduced the resistance of the resulting strains to KM and to related drugs, e.g. G418. 3. Similarly, enzyme activity in the crude extracts of these mutants was substantially reduced as well as the enzyme's affinity for Mg2+ ATP. 4. Alternatively substitutions at a highly c...
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In this study, the effects of bioprocess operation parameters on aromatic amino acid synthesis performance of Bacillus acidocaldarius were investigated. Firstly, in laboratory scale shake-bioreactors, a defined medium was designed in terms of its carbon and nitrogen sources, to achieve the highest cell concentration. Thereafter, the effects of bioprocess operation parameters, i.e., pH and temperature were investigated; and the optimum medium contained (kg m-3): fructose, 8; (NH4)2HPO4, 5; CaCl2, 0.2; KH2PO4...
Synthesis characterization and modification of α-tricalcim phosphate based bone supporting systems
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The constitutive studies of this thesis were achieved and presented in three parts. In the first part, the effects of solid state synthesis process parameters and the impurity content of primary calcium precursor on the cement-type hydration efficiency for the conversion of α-tricalcium phosphate (Ca3(PO4)2 or α-TCP) into hydroxyapatite (Ca10-xHPO4(PO4)6-x(OH)2-x x = 0–1, or HAp) have been investigated (at 37°C). α-TCP was synthesized by thermal processing of stoichiometric amounts of calcium carbonate (CaC...
Citation Formats
N. Şaki, “Xanthene-based artifical enzymes and a dimeric calixpyrrole as a chromogenic chemosensor,” Ph.D. - Doctoral Program, Middle East Technical University, 2004.