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Fluorimetric pH measurement in whole cells of dark aerobic and anaerobic cyanobacteria
Author(s) -
Hinterstoisser Barbara,
Peschek Günter A.
Publication year - 1987
Publication title -
febs letters
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.593
H-Index - 257
eISSN - 1873-3468
pISSN - 0014-5793
DOI - 10.1016/0014-5793(87)80657-9
Subject(s) - cytosol , chemistry , anaerobic exercise , biophysics , divalent , fluorescence , thylakoid , quenching (fluorescence) , intracellular , biochemistry , fluorescein , membrane , cyanobacteria , photochemistry , biology , bacteria , chloroplast , enzyme , physiology , physics , genetics , organic chemistry , quantum mechanics , gene
9‐Aminoacridine and atebrin fluorescence quenching by dark aerobic and anaerobic suspensions of Anacystis nidulans, Plectonema boryanum and Gloeobacter violaceus was determined at external pH 7–9. Individual pH values in cytosol and thylakoid compartments were calculated from the simultaneously different intracellular enrichment factors of the monovalent and the divalent base. Concomitantly, at external pH 4–7 the cytosolic pH was measured with fluorescein diacetate which is taken up and decomposed in the cell by cytosolic hydrolases. The pH‐dependent fluorescence of the free fluorescein, which remains trapped in the cell, monitors the cytosolic pH. The fact that the latter was higher in aerobic than in anaerobic cells, and insensitive to saturating concentrations of dicyclohexylcarbodiimide aerobically, was taken to support the concept of a proton‐translocating respiratory chain in the plasma membrane.