Abstract
Proton nuclear magnetic resonance (1H NMR) spectra of leaves from 50 plant species were obtained at a spectrometer frequency of 470 MHz. Water present in leaf samples gives rise to characteristic spectral patterns. Most species show only one broad 1H NMR peak; however, the leaves of some plants display complex, orientation-dependent spectra in which a common three-line pattern is discerned. The pattern varies with the angle between the leaf surface and the external magnetic field. Proton relaxation measurements show the presence of at least two water compartments in the leaves. The compartments are responsible for different components of the spectral pattern. EPR spectra, obtained at 35 GHz and at a temperature of -180°C, of plant leaf sections are dominated by the strong signals of manganous ions. We find that most plant leaves have isotropic Mn2+ EPR spectra. However, in some species (including ones that exhibit orientation-dependent 1H NMR spectra) we detect orientation-dependent intensities in the forbidden lines; the spectra indicate that Mn2+ ions occupy binding sites with axial or lower symmetry on nonrandomly oriented membranes. Both the NMR and the EPR results suggest that the chloroplasts of some plants are preferentially aligned with respect to the leaf surface.
Keywords: water compartmentalization, chloroplasts, thylakoid membrane, manganous ion
Full text
PDF
Selected References
These references are in PubMed. This may not be the complete list of references from this article.
- Burke M. J. Nuclear magnetic resonance of water in cold acclimating red osier dogwood stem. Plant Physiol. 1974 Sep;54(3):392–398. doi: 10.1104/pp.54.3.392. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Gusta L. V., Fowler D. B., Chen P. A Nuclear Magnetic Resonance Study of Water in Cold-acclimating Cereals. Plant Physiol. 1979 Apr;63(4):627–634. doi: 10.1104/pp.63.4.627. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Macdowall F. D., Buchanan G. W. Estimation of the water of hydration in wintering wheat leaves by proton magnetic resonance. Can J Biochem. 1974 Jul;52(7):652–654. doi: 10.1139/o74-093. [DOI] [PubMed] [Google Scholar]
- Reed G. H., Cohn M. Electron paramagnetic resonance spectra of manganese (II)-protein complexes. Manganese (II)-concanavalin A. J Biol Chem. 1970 Feb 10;245(3):662–664. [PubMed] [Google Scholar]
- Stout D. G., Steponkus P. L. Nuclear magnetic resonance relaxation times and plasmalemma water exchange in ivy bark. Plant Physiol. 1978 Oct;62(4):636–641. doi: 10.1104/pp.62.4.636. [DOI] [PMC free article] [PubMed] [Google Scholar]
- Yocum C. F., Yerkes C. T., Blankenship R. E., Sharp R. R., Babcock G. T. Stoichiometry, inhibitor sensitivity, and organization of manganese associated with photosynthetic oxygen evolution. Proc Natl Acad Sci U S A. 1981 Dec;78(12):7507–7511. doi: 10.1073/pnas.78.12.7507. [DOI] [PMC free article] [PubMed] [Google Scholar]