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The Effect of Water Accessible Paramagnetic Ions on Subcellular Structures Formed in Developing Wheat Photosynthetic Membranes as Observed by NMR and by Sorption Isotherm

100%
Harańczyk H., Leja A., Strzałka K.
Acta Physica Polonica A
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2006
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vol. 109
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issue 3
389-398
EN
The rehydration from the gaseous phase of the developing native or EDTA-washed from unbound and loosely bound paramagnetic ions wheat thylakoid membrane lyophilizate was investigated using hydration kinetics, sorption isotherm, and high power proton relaxometry. Hydration time courses are single exponential for all target humidities. The sorption isotherm is well fitted by the Dent model, with the mass of water saturating primary binding sites equal toΔ M/m_ 0=0.024 and 0.017 for native and EDTA-washed membranes, respectively. Proton free induction decays distinguish: (i) a Gaussian component, S_0, coming from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S_1, from water bound to the primary water binding sites in proximity of water accessible paramagnetic ions; (iii) an exponentially decaying contribution, $L_1$, from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L_2. Sorption isotherm fitted to NMR data shows a significant contribution of water "sealed" in membrane structures (Δ M_s/m_0=0.052 for native and 0.061 for EDTA-washed developing membranes, respectively).
2
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Maturation Process of Photosynthetic Membranes Observed by Proton Magnetic Relaxation and Sorption Isotherm

100%
Harańczyk H., Leja A., Jemioła-Rzemińska M., Strzałka K.
Acta Physica Polonica A
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2009
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vol. 115
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issue 2
526-532
EN
Mild rehydration from the gaseous phase of the developing and mature lyophilized wheat photosynthetic membranes was investigated using hydration kinetics, adsorption isotherm and high power proton relaxometry. Hydration time courses are single exponential for all target air humidities; the hydration time t^h equals to (11.9±3.6) h for the mature membranes, and (17.0±3.2) h for the developing membranes. The sorption isotherm is sigmoidal in form and well fitted using the Dent model; the mass of water saturating primary binding sites equals Δ M/m_0= 0.033±0.013 and 0.025±0.007 for the mature and for the developing membranes, respectively, where m_0 is the dry mass of the sample, and Δ M is mass of water taken up. Proton free induction decays distinguish: (i) an immobilized proton (Gaussian) component, S_0, originating from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S_1, from water bound to the primary water binding sites and localized in proximity of paramagnetic ions; (iii) an exponentially decaying contribution, L_1, from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L_2. A significant contribution of water "sealed" in the structure of lyophilized membrane (from the fraction S_1 and L_1) is detected. The mass of "sealed" water fraction is Δ M_{S}/m_0 = 0.047±0.023 and 0.072±0.021 for the mature and for the developing membranes, respectively.
3
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The Effect of Mild Rehydration on Freeze-Dried Dipalmitoylphosphatidylcholine (DPPC) Multilamellar Membranes as Observed by Proton NMR and Sorption Isotherm

88%
Harańczyk H., Leja A., Nowak P., Baran E., Strzałka K.
Acta Physica Polonica A
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2016
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vol. 129
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issue 2
179-184
EN
Between neighbouring bilayers of lyophilized dipalmitoylphosphatidylcholine (DPPC) multilamellar vesicles the total number of water molecules equals 9 H₂O molecules/1 DPPC molecule. One of these molecules is very tightly bound to the lipid molecule, seven are in immobilized (tightly bound) water fraction whereas the last one belongs to mobile water fraction. The rehydration from the gaseous phase of the DPPC model membranes was investigated using hydration kinetics, sorption isotherm, and high power proton relaxometry. The obtained data for DPPC were compared with these obtained for wheat photosynthetic membranes. Rehydrated photosynthetic membranes differ from DPPC model membranes in hydration kinetics. The average hydration time has a similar value: (22.0 ± 2.8) h (photosynthetic membrane) and (19.8 ± 1.6) h (DPPC), however hydration kinetics was described by one-exponential function for photosynthetic membrane, while for model membrane it shows fine double exponential form. The sigmoidal form of sorption isotherm is better fitted using Dent model than by the Brunauer-Emmett-Teller formula. The Brunauer-Emmett-Teller/Dent deviation parameter b =0.93 either for photosynthetic or for model membranes. The mass of water saturating primary water binding sites equals ΔM/m₀= 0.017 (wheat photosynthetic membranes) and 0.027 (DPPC). The detected by NMR-isotherm study mass of water "sealed" in model membrane structures was about ΔMₛ/m₀=0.182 (about 7-8 H₂O molecules/1 DPPC molecule), and ΔMₛ/m₀= 0.066 for photosynthetic membrane.
4
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Rehydration of Digalactosyldiacylglycerol Model Membrane Lyophilizates Observed by NMR and Sorption Isotherm

88%
Harańczyk H., Bacior M., Jamróz J., Jemioła-Rzemińska M., Strzałka K.
Acta Physica Polonica A
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2009
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vol. 115
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issue 2
521-525
EN
The initial stages of rehydration of digalactosyldiacylglycerol model membrane lyophilizates were observed using hydration kinetics, sorption isotherm, and high power proton relaxometry (at 30 MHz). Hydration time courses are single exponential and the sorption isotherm is sigmoidal in form. The mass of water saturating primary binding sites equals Δ M/m_0= 0.019±0.001. Proton free induction decays distinguish (i) immobilized protons of solid matrix of lyophilizate, signal S_0; (ii) protons of water fraction tightly bound to the lyophilizate surface, L_1; and (iii) mobile protons of loosely bound water pool, L_2. Hydration dependence of total water signal (L_1+L_2)/S_0 shows the presence of water fraction "sealed" in liposome structures, which equals Δ M_{S}/m_0 = 0.092±0.007.
5
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Mössbauer Studies of Cu(II) Ions Interaction with the Non-Heme Iron and Cytochrome b_{559} in a Chlamydomonas reinhardtii PSI Minus Mutant

76%
Burda K., Kruk J., Strzałka K., Stanek J., Schmid G., Kruse O.
Acta Physica Polonica A
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2006
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vol. 109
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issue 3
237-247
EN
Mössbauer spectroscopy was applied, for the first time, to study the interaction of copper ions with the non-heme iron and the heme iron of cytochrome b_{559} in photosystem II thylakoids isolated from a Chlamydomonas reinhardtii photosystem I minus mutant. We showed that copper ions oxidize the heme iron and change its low spin state into a high spin state. This is probably due to deprotonation of the histidine coordinating the heme. We also found that copper preserves the non-heme iron in a low spin ferrous state, enhancing the covalence of iron bonds as compared to the untreated sample. We suggest that a disruption of hydrogen bonds stabilizing the quinone-iron complex by Cu^{2+} is the mechanism responsible for a new arrangement of the binding site of the non-heme iron leading to its more "tense" structure. Such a diamagnetic state of the non-heme iron induced by copper results in a magnetic decoupling of iron from the primary quinone acceptor. These results indicate that Cu does not cause removal of the non-heme iron from its binding site. The observed Cu^{2+} action on the non-heme iron and cytochrome b_{559} is similar to that previously observed forα-tocopherol quinone.
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