In 1956 Edwin Krebs and Edmond Fischer discovered that adenosine triphosphate (ATP) is required for the conversion of glycogen phosphorylase b to glycogen phosphorylase a. While investigating the action of adrenaline on glycogenolysis the next year, Sutherland and Walter Wosilait reported that inorganic phosphate is released when the enzyme liver phosphorylase is inactivated; but when it is activated, it incorporates a phosphate.[1] The “active factor” that the hormones produced[2] was finally purified in 1958, and then identified as containing a ribose, a phosphate, and an adenine in equal ratios.