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Macrocyclic complexes as models for copper(II) bonding in cupredoxins: Proof of concept
Ulrichová, Tereza ; Hermann, Petr (advisor) ; Hudeček, Jiří (referee)
Currently, modified electron transport metaloproteins with presence ion Cu(II) in their active site are most commonly used to study kinetics of electron transfer. One of the most studied model protein is cupredoxin azurin from P. aeruginosa with standard redox potential approximately 310-360 nm (depends on experimental conditions and techniques). Ion Cu(II) in azurin is coordinated by the side chain atoms of His46 , His117 , Cys112 , Met121 and carbonyl of Gly45 . The aim of this work was to prepare macrocyclic ligand, 1-[1H-imidazol-2- yl)methyl]-1,4,7-triazacycklononanu (LIM ), which would be able to form stable complexes with both of copper ions Cu(II) and Cu(I). Such as macrocyclic complexes could be utilized as low molecular models of active sites in proteins. The ligand was prepared using five-step synthesis employing protection of macrocycle, reduction and subsequent bromation of 1H- imidazol-2-karbaldehyd, and following alkylation reaction. Deprotection of macrocycle revealed final product of ligand. All reaction intermediates and prepared ligand were characterized by NMR and MS. Potentiometric titrations determined ligand protonation constant (log K1 = 10,62, log K2 = 6,65, log K3 = 4,91), which describe acid-base properties of a ligand in an aqueous solution. Similarly, the coordination...
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Macrocyclic complexes as models for copper(II) bonding in cupredoxins: Proof of concept
Ulrichová, Tereza ; Hermann, Petr (advisor) ; Hudeček, Jiří (referee)
Currently, modified electron transport metaloproteins with presence ion Cu(II) in their active site are most commonly used to study kinetics of electron transfer. One of the most studied model protein is cupredoxin azurin from P. aeruginosa with standard redox potential approximately 310-360 nm (depends on experimental conditions and techniques). Ion Cu(II) in azurin is coordinated by the side chain atoms of His46 , His117 , Cys112 , Met121 and carbonyl of Gly45 . The aim of this work was to prepare macrocyclic ligand, 1-[1H-imidazol-2- yl)methyl]-1,4,7-triazacycklononanu (LIM ), which would be able to form stable complexes with both of copper ions Cu(II) and Cu(I). Such as macrocyclic complexes could be utilized as low molecular models of active sites in proteins. The ligand was prepared using five-step synthesis employing protection of macrocycle, reduction and subsequent bromation of 1H- imidazol-2-karbaldehyd, and following alkylation reaction. Deprotection of macrocycle revealed final product of ligand. All reaction intermediates and prepared ligand were characterized by NMR and MS. Potentiometric titrations determined ligand protonation constant (log K1 = 10,62, log K2 = 6,65, log K3 = 4,91), which describe acid-base properties of a ligand in an aqueous solution. Similarly, the coordination...
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Structure-functional study of electrotransport protein systems
Tuzhilkin, Roman ; Šulc, Miroslav (advisor) ; Kukačka, Zdeněk (referee)
Electron transport processes are an extremely important field of study in modern biochemistry and structural/functional proteomics. Azurin is one of the most utilised model systems for study of redox and electron transport processes in proteins. We have utilised photo-induced crosslinking (PIXL) to study oligomerization of azurin in solution and the effect of L-2-amino-5,5-azi-hexanoic acid (photo-Met) - a structural photoinducible analogue of canonical amino acid Met - on electron transport processes in azurin. The optimisation of expression conditions of recombinant azurin in auxotrophic E. coli B834 cells was done to maximise photo-Met incorporation percentage in azurin sequence (70% incorporation was measured via MALDI-TOF mass spectrometry). Through the optimisation of purification protocol (example: cell disintegration, acid precipitation of proteins, adding metallic ligand during cell sonication) we have increased the purity and yield of final product and reduced the purification time. Final preparations (wild-type azurin (WT) with Met, WT with photo-Met and "All-Phe" mutant (all Trp/Tyr replaced by Phe) with photo-Met) were exposed to intense UV-light (PIXL) and evaluated via UV-VIS spectroscopy and SDS-PAGE. During PIXL experiment some photo-Mets incorporated into azurin were able to: (i)...
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