ANTAGONISM OF THE INHIBITORY ACTION OF AMINOSALICYLIC ACID ON MYCOBACTERIUM TUBERCULOSIS BY METHIONINE, BIOTIN AND CERTAIN FATTY ACIDS, AMINO ACIDS, AND PURINES

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Abstract
Inhibition of M. tuberculosis by p-aminosalicylic acid was reversed competitively by p-aminobenzoic acid. Noncompetitive reversal of inhibition by p-aminosalicylic acid was effected by methionine and biotin when the concentration of the inhibitor did not exceed 0.5 [mu]g/ml. Reversal of inhibition produced by all concentrations of p-aminosalicylic acid occurred in media containing methionine and biotin following the addition of fatty acids (C5 - Cl8), of certain amino acids (valine, norvaline, leucine, norleucine, isoleucine, phenylalanine), and of purines (hypoxanthine, guanine). The synthesis of methionine and biotin appear to be mediated by p-aminobenzoic acid and inhibited by p-aminosalicylic acid. Purines may be the primary product of a third reaction inhibited by p-aminosalicylic acid and mediated by p-aminobenzoic acid.