Die Steuerung der Arginasewirkung durch Sauerstoff. 9. Mitteilung zur Kenntnis der Arginase.

Abstract

Hydrolysis of arginin by arginase in vivo is repressed by thyroxin, which stimulates metabolism; hence the authors studied the influence of oxygen on the above named system. The enzyme was obtained from normal livers of dog, pig, cow, guinea-pig, rabbit and rat, from kidneys of the hen, and from mouse carcinoma. The inhibiting action of oxygen was counteracted by N2, H2, and CO. Activation by cystein, glutathione and ferro-salts was indirect: it consisted in taking up oxygen, for in an oxygen-free milieu the enzyme was not activated by SH-groups. The idea that ferrous compounds take an active part in the regulating mechanism of argininhydrolysis in the organism is rejected, as CO, N2 quantitatively had the same activating influence while in the former case all the iron compounds in the cells gave carbonyl compounds. The arginase of tumors was much more sensitive towards oxygen than that from normal tissue, but under aerobic conditions, no difference in pH-optimum was found. The action of arginase was strongly inhibited by minute doses of heavy metals.