Absorption changes accompanying cleavage of the Schiff base bond by 0.2 M hydroxylamine in gloeobacter rhodopsin before (A and B) and after reconstitution with salinixanthin (C, D) at pH 7.2 in the dark. A and C, absolute spectra; B and D, difference spectra. The spectra shown in A were taken at 0, 5, 10 15, 30, 45, 60, 90 120, 180 and 240 min after addition of hydroxylamine. The spectra in B obtain by subtraction of initial spectrum (at zero time) from the rest. The spectra shown in C were taken at 0, 5, 10, 15, 30, 60 and 90 min.