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

H. Harańczyka, A. Lejaa and K. Strzałkab aInstitute of Physics, Jagiellonian University, Reymonta 4, 30-059 Kraków, Poland bFaculty of Biotechnology, Jagiellonian University, Gronostajowa 7, 30-387 Kraków, Poland

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Received: 2005 20 05;

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/m0=0.024 and 0.017 for native and EDTA-washed membranes, respectively. Proton free induction decays distinguish: (i) a Gaussian component, S0, coming from protons of solid matrix of lyophilizate; (ii) a Gaussian component, S1, from water bound to the primary water binding sites in proximity of water accessible paramagnetic ions; (iii) an exponentially decaying contribution, L1, from water tightly bound to lyophilizate surface; and (iv) exponentially decaying loosely bound water pool, L2. Sorption isotherm fitted to NMR data shows a significant contribution of water "sealed" in membrane structures (Δ Ms/m0=0.052 for native and 0.061 for EDTA-washed developing membranes, respectively).

DOI: 10.12693/APhysPolA.109.389 PACS numbers: 82.56.Na, 87.16.Dg