Cytochromec and evolution of the energy acquiring system

The reactivity of cytochromesc derived from various organisms withPseudomonas aeruginosa nitrite reductase and cow cytochrome oxidase has been studied.Generally, cytochromesc isolated from primitive organisms react very rapidly with the bacterial nitrite reductase but do not react with cow cytochrome oxidase while those from higher organisms react poorly with the nitrite reductase but react very rapidly with the animal oxidase. The reactivity of cytochromec with the bacterial nitrite reductase reflects very well the evolutionary position of the organism from which it is isolated, while that with cow cytochrome oxidase seems to be related to the extent of adaptation of the parent organism to molecular oxygen. The results obtained in the present investigation suggests that cytochromec molecule which reacts very rapidly with the bacterial nitrite reductase but does not react with cow cytochrome oxidase has evolved to that which reacts very poorly with the nitrite reductuase but reacts very rapidly with the animal oxidase. It is also inferred that the evolution of cytochromec molecule may be caused by the evolution of cytochrome oxidase, and that the latter may be intimately related to genesis of molecular oxygen in the biosphere.Special Symposium on Photochemistry and the Origins of Life, Sixth International Congress on Photobiology, Bochum, Germany.