NMR Study of Chloroplast Water in Acer platanoides: Water Exchange at Membrane-Bound Sites and Across the Chloroplast Envelope Membrane

Abstract:

Nuclear magnetic resonance (NMR) spin relaxation techniques were used to measure the rate of water exchange across the chloroplast envelope membrane and to detect exchange of water-hydrogens between the bound and fluid states in Acer platanoides shade leaves. Results indicate that individual water molecules resided within a chloroplast for 320 ± 65 ms, on average, before exchanging through the envelope, and that exchangable bound hydrogens are at least six times more abundant in the chloroplast than in the nonchloroplast compartments.

Acer platanoides L. - chloroplast - NMR - water exchange

References

• 01 Campbell,  I. O.,, Dobson,  C. M.,, Ratcliffe,  R. G.,, and Williams,  R. J. P.. (1978);  Fourier transform NMR pulse methods for the measurement of slow-exchange rates.  Journal of Magnetic Resonance. 29 397-417
• 02 Dilley,  R. A.,, Theg,  S. M.,, and Beard,  W. A.. (1987);  Membrane-proton interactions in chloroplast bioenergetics: localized proton domains.  Annual Review of Plant Physiology. 38 347-389
• 03 Hinton,  D. P., and Bryant,  R. G.. (1994);  Measurement of protein preferential solvation by Z-spectroscopy.  Journal of Physical Chemistry. 98 7939-7941
• 04 Koenig,  S. H., and Brown,  R. D. III. (1993);  A molecular theory of relaxation and magnetization transfer: application to cross-linked BSA, a model for tissue.  Magnetic Resonance in Medicine. 30 685-695
• 05 Levy,  G. C., and Peat,  I. R.. (1975);  An experimental approach to accurate carbon-13 spin-lattice relaxation measurements.  Journal of Magnetic Resonance. 18 500-521
• 06 Maurel,  C.. (1997);  Aquaporins and water permeability of plant membranes.  Annual Review of Plant Physiology and Plant Molecular Biology. 48 399-429
• 07 McCain,  D. C.. (1995);  The combined effect of light and water stress on chloroplast volume regulation.  Biophysical Journal. 69 1105-1110
• 08 McCain,  D. C.. (1997);  Rates and pathways for water diffusion and bulk flow through leaf tissue: a new technique for an old problem.  Plant Science. 125 113-117
• 09 McCain,  D. C.,, Croxdale,  J.,, and Markley,  J. L.. (1988);  Water is allocated differently to chloroplasts in sun and shade leaves.  Plant Physiology. 86 16-18
• 10 McCain,  D. C.,, Croxdale,  J.,, and Markley,  J. L.. (1993);  The spatial distribution of chloroplast water in Acer platanoides sun and shade leaves.  Plant, Cell and Environment. 16 727-733
• 11 McCain,  D. C., and Markley,  J. L.. (1985 a);  A theory and a model for interpreting the proton nuclear magnetic resonance spectra of water in plant leaves.  Biophysical Journal. 48 687-694
• 12 McCain,  D. C., and Markley,  J. L.. (1985 b);  Water permeability of chloroplast envelope membranes: in vivo measurement by saturation-transfer NMR.  FEBS Letters. 183 353-357
• 13 McCain,  D. C.,, Selig,  T. C.,, Govindjee, , and Markley,  J. L.. (1984);  Some plant leaves have orientation-dependent EPR and NMR spectra.  Proceedings of the National Academy of Sciences (USA). 81 748-752
• 14 Sharp,  R. R., and Yocum,  C. F.. (1980);  The kinetics of water exchange across the chloroplast membrane.  Biochimica et Biophysica Acta. 592 169-184