TY - JOUR T1 - THE EFFECT OF COPPER IONS AND CERTAIN THIOUREAS ON ENZYME INDUCTION AND AMMONIA ASSIMILATION IN A MYCOBACTERIUM JF - Journal of Pharmacology and Experimental Therapeutics JO - J Pharmacol Exp Ther SP - 93 LP - 98 VL - 119 IS - 1 AU - Frederick Bernheim Y1 - 1957/01/01 UR - http://jpet.aspetjournals.org/content/119/1/93.abstract N2 - Certain thioureas inhibit enzyme induction only when copper ions in noninhibitory concentrations have been added to the cells before the drugs. Premixing copper and thioureas before addition decreases the inhibition. Similar effects are obtained with ethylxanthate. The substituted thioureas inhibit ammonia assimilation and copper ions do not enhance the effect. Thiourea inhibits only in the presence of copper. Thiouracil and versene are inactive but catechol behaves like the substituted thioureas. Other metal ions cannot replace copper. Because copper must be added to the cells before the thioureas and because of the large molar differential between copper and the drugs the results cannot be explained entirely on the basis of chelate formation. ER -