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4 Acta Physica Polonica A

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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

2009

tom 115

nr 2

526-532

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.

Bound Water Structure on the Surfaces of Usnea antarctica as Observed by NMR and Sorption Isotherm

100%

Harańczyk H. , Pietrzyk A. , Leja A. , Olech M.

Acta Physica Polonica A

2006

tom 109

nr 3

411-416

Hydration courses and proton free induction decays are recorded at 30 MHz for Usnea antarctica thalli hydrated from gaseous phase. NMR data combined with gravimetry allow one to distinguish two fractions of tightly bound water, and loosely bound/free water pool. No water fraction "sealed" in thallus structures is present in U. antarctica.

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

2006

tom 109

nr 3

389-398

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).

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

2016

tom 129

nr 2

179-184

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.