“…Albumin has been shown to be important in inhibiting BR IXa P XIIIct P lllct isomeiization McDonagh, 1975aMcDonagh, , 1976a, and it is apparently important in BR photochemistry leading to the "443", "430" or other pigment(s) (Kapitulnik et al, 1973(Kapitulnik et al, , 1976McDonagh, 1974;McDonagh and Palma, 1976;Pedersen et al, 1977) EDTA added to pH 8.5 buffered BR solution has a marked protective influence against BR photodisappearance (Ostrow and Branham, 1970), but Zni2 or Fe+2 ions accelerate BR photo-decay (Ostrow, 1972b). Such divalent metals could be important in altering the conformation (hence reactivity) of BR (Velapoldi and Menis, 1971;Hutchinson et al, 1973).…”