Para magnetic manganese and associated resonances in isolated cucumber cucumis sativus cultivar long green cotyledons in light and dark
Bharti, S.; Singh, Y.D.; Laloraya, M.M.
Journal of Experimental Botany 29(112): 1085-1090
ISSN/ISBN: 0022-0957 Accession: 006060350
ESR spectra of cucumber cotyledons show that paramagnetic manganese exists in 3 different forms in biological systems. Different resonances appear along with the Mn signal. Resonances due to Cu ions appear along with the third peak of the Mn signal from the low-field side of the spectrum. Some photo-induced signals appear superimposed over the fourth peak of the Mn sextet corresponding to m/2. The first peak, however, remains unaffected by any detectable resonance and line broadening effects. Since signal height is taken as a measure of Mn concentration, the height of the fourth peak or averaging the height of all the 6 peaks may give false results in biological systmes. Mn feeding has a general promotive effect on the 6 peaks of Mn(II) and the first peak shows most marked changes. The height of the first peak, can safely be taken as a measure of Mn concentration in a tissue. The resonances causing baseline drift of the sextet disappear with the growth of the cotyledons in light. The loss of their paramagnetic property may either be due to complex formation or change in their redox state.