Effects of Thyroxine, 3,5-Diiodothyronine and Thyronine on Ascorbic Acid Oxidation

Abstract

Crystalline thyroxine and sodium-1-thyroxine pentahydrate accelerate the velocity of the uptake of O2 in the ascorbic acid-ascorbic acid oxidase system. 3,5-Diiodothyronine has a slight effect on this system while thyronine has no effect in the concns. used in these expts. Crystalline thyroxine and Na-1-thyroxine pentahydrate inhibit the velocity of uptake of O2 in the ascorbic acid-cupric chloride system proportional to their concns. The molar ratio of thyroxine to cupric chloride is approx. three. The 3,5-diiodothyronine has a slight effect on this system while thyronine has no effect. The mechanisms of these reactions are discussed in terms of a possible free radical formation of thyroxine.