Calcium binding by spinach stromal proteins
Kreimer G, Surek B, Woodrow IE, Latzko E (1987)
Publication Status: Published
Publication Type: Journal article
Publication year: 1987
Journal
Publisher: Springer Verlag (Germany)
Book Volume: 171
Pages Range: 259-265
Journal Issue: 2
DOI: 10.1007/BF00391103
Abstract
Calcium binding to spinach (Spinacia oleracea L.) stromal proteins was examined by dual-wavelength spectrophotometry using the metallochromic indicator tetramethylmurexide. The data are consistent with the existence of at least two, probably independent, classes of binding sites. The total number of binding sites varied between 90–155 nmol·mg−1 protein with “average” binding constants of 1.1–2.7·mM−1. Both Mg2+ and La3+ inhibited calcium binding competitively, with “average” inhibitor constants of 0.26·mM−1 and 39.4·mM−1, respectively; an increase in the potassium concentration up to 50 mM had no effect. In a typical experiment a decrease in pH (7.8 to 7.1) resulted in a decrease in the total number of calcium binding sites from 90 to 59 nmol·mg−1 protein, but in an increase of the “average” affinity from 2.7 to 4.5·mM−1. Calculations, using these data and those of Gross and Hess (1974, Biochim. Biophys. Acta 339, 334–346) for binding site I of washed thylakoid membranes, showed that the free-Ca2+ concentration in the stroma under dark conditions, pH 7.1, is higher than under light conditions, pH 7.8. The physiological relevance of the observed calcium binding by stromal proteins is discussed.
Authors with CRIS profile
Involved external institutions
Westfälische Wilhelms-Universität (WWU) Münster
Germany (DE)
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Australia (AU)
Germany (DE)
Commonwealth Scientific and Industrial Research Organisation (CSIRO)
Australia (AU)
How to cite
APA:
Kreimer, G., Surek, B., Woodrow, I.E., & Latzko, E. (1987). Calcium binding by spinach stromal proteins. Planta, 171(2), 259-265. https://dx.doi.org/10.1007/BF00391103
MLA:
Kreimer, Georg, et al. "Calcium binding by spinach stromal proteins." Planta 171.2 (1987): 259-265.
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