Figure 1. Absorbance spectra of thylakoid membranes and effects of MgCl₂ titration on light scattering.

A, the spectra of native thylakoid suspensions from wild type, stn7, stn8 and stn7stn8, as indicated, in the presence of 5 mM MgCl₂. Representative spectra are superimposed in the upper panel. Lower panel demonstrates spectra of the same thylakoid membranes after extraction with 80% acetone. B, light-scattering changes as a function of MgCl₂ titration: the representative spectra at 0, 5 and 30 mM MgCl₂, as indicated, are shown for wild type (upper panel) and stn8 (lower panel) thylakoid membranes. C, titration of the light-scattering changes in the thylakoid membranes from wild type, stn7, stn8 and stn7stn8, as indicated, using 0, 5, 10, 15, 20 and 30 mM MgCl₂ and normalization of absorbance at 580 nm to the 678 nm signal. Error bars represent S.D. of at least three independent experiments.