The assimilation of amino acids by bacteria. 24. Inhibitors of incorporation of glycine in disrupted staphylococcal cells.

In previous papers of this series (Gale & Folkes, 1955a, b) a description has been given of a preparation of disrupted staphylococcal cells which can be used to study the dependence on nucleic acid of protein-synthesis and amino acid-incorporation reactions. Removal of nucleic acid from the preparation results in marked decrease in the incorporation of certain amino acids; the incorporation can be restored by addition of staphylococcal nucleic acid to the incubation mixture. The action of ribonucleic acid (RNA) in restoring incorporation is not abolished by the action of ribonuclease, and active materials can be separated from the digestion products. In the case of the incorporation of glycine, fractionation ofRNA digests has led to the separation of a highly active 'incorporation factor' whose properties are not those of any known nucleotide or nucleoside (Gale, 1957). In the present paper an investigation ofthe action of various inhibitors on the incorporation of glycine in the disrupted-cell preparation is reported. The actions of chelating agents and analogues of purines, pyrimidines and growth factors were studied in an attempt to throw light on the possible nature of components of the system, including the incorporation factors. Various antibiotics and antimicrobial drugs were included in the survey, since the disrupted-cell preparation affords a means of studying the action of such selective agents in the absence of penetration barriers which may be largely responsible for their selective nature. Of the synthetic substances investigated, 8hydroxyquinoline (oxine) and various derivatives of benzimidazole have proved to be potent inhibitors. The antibacterial action of oxine has been investigated by Albert, Gibson & Rubbo (1953), who concluded that oxine itself is non-toxic but forms toxic chelates with certain heavy metals, iron in particular, and that the toxicity in a given medium is determined by the relative amounts of oxine and metal. Woolley (1944) showed that benzimidazole and certain derivatives thereof inhibited the growth of yeasts and bacteria and that the action could be