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Structural analysis of extrinsic proteins from the oxygen-evolving complex of photosystem II from higher plants
KOHOUTOVÁ, Jaroslava
All life on earth depends mainly on the presence of oxygen. Largest producers of oxygen are green plants, cyanobacteria and algae. Oxygen is released from the oxygenevolving complex of photosystem II during photosynthesis and it is used in cellular respiration of all life complexes. The oxygen-evolving complex of photosystem II has the same function in each photosynthetic organism, but it has a different composition and organization of extrinsic proteins; only PsbO protein is ubiquitous in all known oxyphototrophs. Until now only low resolution electron microscopy structural models of plant PSII and crystal structures of cyanobacterial PSII are available. Higher plant extrinsic proteins (PsbP, PsbQ and PsbR) are structurally unrelated, non-homologues to the cyanobacterial extrinsic proteins (PsbO, PsbU and PsbV) and this is the reason why it is not possible to predict arrangement of these proteins on the lumenal site of higher plant PSII. Recently, models differ mainly in the structure of the oxygen-evolving complex, which could be resolved by determination of the exact binding sites for extrinsic proteins. An other question evolves: if the difference in the oxygen-evolving complex composition is the result of evolution or adaptation of photosynthetic organisms to their environment. Structural knowledge of extrinsic proteins that could help to resolve the location and subsequently the function of extrinsic proteins is still incomplete. From this case,structural analysis, interactions and probably arrangement of proteins PsbP and PsbQ was studied and is described in detail in this thesis.
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Study of gel electrolytes properties by MR methods
Kořínek, R. ; Vondrák, Jiří ; Bartušek, Karel ; Mrnka, M.
In this paper are introduced basic methods for measuring the properties of the gel structure during polymerization, particularly relaxation times T1, T2 spin density and diffusion coefficients. We can obtain these parameters using the MR pulse sequences. To measure of relaxation time T1 are used SR techniques (Saturation Recovery) and IR techniques (Inversion Recovery) usually. To measure of relaxation time T2 can be used SE (Spin Echo) technique. To measure diffusion coefficinets are used PFG-SE and PFG-SSE methods (Pulsed Field Gradient Spin Echo a Pulsed Field Gradient Stimulated Echo) and of course their modification. Experiment itself is described sample preparation of gel electrolytes and to measure their relaxation times.
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Korekční metoda pro nehomogenní magnetické pole
Hadinec, M. ; Bartušek, Karel
In this work, we developed a method, which is used for approximation of basic magnetic field B0 inside a specific spherical volume. The coefficients of spherical function expansion obtained from approximation process can be used for determination of shimming currents which are feeding correction coils of tomograph.
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Influence of Isochinolinic A-Fraction (Phenolic CHCl3 Insoluble Cl- > Salts) Alkaloids from Corydalis Cava(Fumariaceae) on Cholinesterases
Chlebek, J. ; Musilová, L. ; Jun, D. ; Opletal, L. ; Kurfürst, Milan ; Schraml, Jan ; Dohnal, V. ; Jahodář, L.
From 12 kg of Corydalis cava bulbs, ethanolic extract was prepared. From this extract, pure alkaloid concentrates. Tertiary bases of average basicity (extract A, 200g) were disolved in hydrochloric acid and two fractions were separated, based on solubility in chloroform. Both fractions were further resoluted to phenolic and non-phenolic bases. Their structure was determined by MS and NMR. Effectivity of obtained compounds was evaluated in vitro, or determined by standard IC50 inhibition test. Human erythrocytal AChE and serum BuChE were used as source ov AChE. Activity was measured spectrophotometrically using standard Elman method. Results were compared to values of IC50 of reference compounds – terapeutic inhibitors (donepezil, rivastigmin, galanthamin, huperzin A).
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