Controlling Effect of Salts on the Activity of the Cytochrome Oxidase

Abstract

ACCORDING to the theory of anion respiration¹, the activity of the cytochrome system is controlled by the activity (concentration) of movable salt anions in the surroundings. With the aid of a new spectrophotometric technique it has been shown that in living wheat roots the oxidation reduction balance of the cytochromes a (oxidase), c and b is moved towards a higher state of oxidation by a change of the medium from distilled water to salt solutions (potassium chloride or nitrate, calcium nitrate, etc.). On removal of the salts the cytochromes revert to a more reduced state. From the automatic recording of the time-course of the phenomena, it was clearly shown that the change in the oxidation–reduction balance of the cytochromes starts simultaneously with the absorption of the salt ions. The fundamental fact that the coenzymatic effect is exerted by salt anions was established by earlier investigations on the effect of salts on the cyanide-sensitive part of respiration². It was shown that this part of respiration is enhanced only if anions are absorbed; absorption of cations only had no effect on it.