[The effect of fumaric acid monoethylester on the synthesis of nucleic acids and proteins of PHA-stimulated human lymphocytes (author's transl)].

Fumaric acid monoethylester (FAME) inhibits the incorporation of 14C-Thymidin, 14C-Uridin, 14C-Alanin and 14C-Leucin into acid-insoluble biopolymers of cultivated PHA-stimulated human lymphocytes. At high concentrations of FAME (500 mug/ml culture medium) the inhibition of nucleic acid synthesis is 6 times higher on the average than the inhibition of protein synthesis. However, the application of the cis-isomer, maleic acid monoethylester (MAME), results in an increase of the incorporation rate of the labelled precursors into the RNA and DNA. This is 3.5--9.3 times higher than after application of FAME. The results demonstrate the specific inhibition by FAME. The rate of labelling of nucleic acids is decreased above 10 mug FAME/ml culture medium and in the case of MAME above 50 mug/ml medium. As an explanation of the specific action of FAME its influence on the enzymes of the nucleic acid synthesis, the citric acid cycle or a faulty synthesis of enzymes are discussed.