“…These initial observations were confirmed and extended in several laboratories (Erixon and Butler, 1971a and b;Boardman et al, 1971;Kitajama and Butler, 1973;Wessels et al, 1973). It now appears that both the high potential (Em = +350mV) from (Knaff and Arnon, 1971 ;Boardman et al, 1971;Okayama and Butler, 1972b) and low potential (Em = +50mV) from (Wessels et al, 1973) of the cytochrome can be oxidized at liquid nitrogen temperature. As the temperature is raised above 77 K, the extent of cytochrome b559 photooxidation decreases.…”