Figure 2.

³¹P-NMR spectra of isolated spinach thylakoid membranes. Thylakoids isolated and suspended in a sorbitol-based isotonic medium (6.3 mg/ml chlorophyll (a + b) content (Chl)), the first 3 hours are plotted (a); thylakoids isolated and suspended in a NaCl-based isotonic medium (4.0 mg/ml Chl) (b). The spectra were recorded for 1 hour, using, the 300 MHz NMR spectrometer. In (b), the measured spectra are averaged for 3-hour periods partly because of the lower signal-to-noise ratio in the NaCl-based sample, which is due to dielectric and conductive losses in the rf efficiency, and partly because of the larger stability of the sample compared to the sorbitol-based sample. For further details, see Materials and methods.