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Effects of Magnesium on Intact Chloroplasts: I. EVIDENCE FOR ACTIVATION OF (SODIUM) POTASSIUM/PROTON EXCHANGE ACROSS THE CHLOROPLAST ENVELOPE
Journal article   Open access   Peer reviewed

Effects of Magnesium on Intact Chloroplasts: I. EVIDENCE FOR ACTIVATION OF (SODIUM) POTASSIUM/PROTON EXCHANGE ACROSS THE CHLOROPLAST ENVELOPE

Steven C Huber and Wendy Maury
Plant physiology, Vol.65(2), pp.350-354
02/01/1980
DOI: 10.1104/pp.65.2.350
PMCID: PMC440325
PMID: 16661188
url
https://doi.org/10.1104/pp.65.2.350View
Published (Version of record) Open Access

Abstract

Exogenous Mg2+ (2 millimolar) altered the stromal pH of intact spinach chloroplasts. Without added KCl in the medium, Mg2+ decreased the stromal pH in the light by approximately 0.3 pH unit. External KCl (25 millimolar) largely prevented the acidification caused by Mg2+. Effects on the stromal pH were not caused by changes in H+ pumping across the thylakoid membrane because Mg2+ had no effect on the light-induced quenching of atebrin fluorescence by intact chloroplasts. However, Mg2+ affected H+ fluxes across the envelope. Addition of Mg2+ to intact chloroplasts in the dark caused a significant acidification of the medium that was dependent on the presence of K+.
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