Dalal, Fram R. (University of Pennsylvania, Philadelphia), Ronald E. Gots, and Joseph S. Gots. Mechanism of adenine inhibition in adenine-sensitive mutants of Salmonella typhimurium. J. Bacteriol. 91: 507-513. 1966.-The inhibition of growth of Salmonella typhimurium by adenine was studied with three adenine-sensitive mutants. These mutants were acutely sensitive to inhibition by adenine, were prototrophic in their growth requirements, and represented mutational events in three different genetic loci. In all cases, inhibition by adenine was relieved noncompetitively by thiamine (or its pyrimidine moiety), pantothenate (or its pantoyl moiety), and methionine alone or, more efficiently, in the presence of lysine. Kinetics of reversal indicated that adenine inhibited the synthesis of the reversing agents, probably at the level of a common factor required for their syntheses, such as the folic acid coenzymes. Support for this inference has been found by the facts that one of the mutants was identified as a partial auxotroph for p-aminobenzoic acid, and sulfadiazine could sensitize the wild type to acute inhibition by adenine.