Journal article


Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase


Publication Details
Author(s): Kreimer G, Melkonian M, Holtum J, Latzko E
Publisher: American Society of Plant Biologists
Publication year: 1988
Volume: 86
Journal issue: 2
Pages range: 423-428
ISSN: 0032-0889

Abstract

Light-mediated activation of fructose-1,6-bisphosphatase (EC 3.1.3.11) in intact spinach chloroplasts (Spinacia oleracea L.) is enhanced in the presence of 10−5molar external free Ca2+. The most pronounced effect is observed during the first minutes of illumination. Ruthenium red, an inhibitor of light-induced Ca2+ influx, inhibits this Ca2+ stimulated activation. In isolated stromal preparations, the activation of fructose-1,6-bisphosphatase is already enhanced by 2 minutes of exposure to elevated Ca2+ concentrations in the presence of physiological concentrations of Mg2+ and fructose-1,6-bisphosphate. Maximal activation of the enzyme is achieved between 0.34 and 0.51 millimolar Ca2+. The Ca2+ mediated activation decreases with increasing fructose-1,6-bisphosphate concentration and with increasing pH. The data are consistent with the proposal that the illumination of chloroplasts leads to a transient increase of free stromal Ca2+. In dark-kept chloroplasts the steady-state concentration of free stromal Ca2+ is 2.4 to 6.3 micromolar as determined by null point titration. These observations support our previous proposal that light-induced Ca2+ influx into chloroplasts does not only influence the cytosolic concentration of free Ca2+ but also regulates enzymatic processes inside the chloroplast.



How to cite
APA: Kreimer, G., Melkonian, M., Holtum, J., & Latzko, E. (1988). Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase. Plant Physiology, 86(2), 423-428. https://dx.doi.org/10.1104/pp.86.2.423

MLA: Kreimer, Georg, et al. "Stromal Free Calcium Concentration and Light-Mediated Activation of Chloroplast Fructose-1,6-Bisphosphatase." Plant Physiology 86.2 (1988): 423-428.

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