Deacetylation of acetamido compounds by tissue extracts.

Several workers have provided evidence that deacetylation occurs both in vivo and in vitro. Abbott (1942) found that, when N-acetylglycine and sodium benzoate were administered orally to rabbits, the increase in hippuric acid excretion was only slightly less than when the corresponding amount of glycine was given with the benzoate. Elson, Goulden & Warren (1946) found that the rat deacetylated Nacetanilide almost completely. Krebs, Sykes & Bartley (1947) showed that injected N4-acetylsulphamezathine was deacetylated to a considerable extent by the pigeon, dog and cat. Some aromatic acetamido compounds appear to undergo slight deacetylation in the rabbit. This is ptobably largely due to spontaneous hydrolysis (cf. Krebs et al; 1947; Bray, Lake & Thorpe, 1949). Deacetylation by tissues in vitro has also been recorded. Kimura (1929) observed the deacetylation of certain aliphatic acetamido acids at pH 7-0--72. Dog liver hydrolysed N-acetyl-DL-leucine more readily than it did N-acetylglycine, although rabbit and-ig liver hydrolysed both compounds to. approximately the same extent. Michel, Bernheiin & Bernheim (1937) showed deacetylase activity in dog, cat, rabbit, rat and ox liver and in rat kidney. Their preparations hydrolysed N-acetyl-L-tyrosine and N-acetyl-L-leucine more readily than they did acetanilide. Kohl & Flynn (1940) showed that rat liver preparations hydrolysed N4-acetylsulphanilamide at pH 7*5, and Shaffer (1942) studied deacetylation of acetamidosulphonamides by chicken kidney. Krebs et ac. (1947) showed that sheep kidney, liver and intestinal mucosa and pigeon liver were active in hydrolysing acetamidosulphonamides at pH 7-3. Bray, James, Raffan, Ryman & Thorpe (1949) and Bray, James & Thorpe (1949) noted differences in the action of liver and kidney preparations of different species towards N-acetylglycine and N-acetanilide which led them to believe that different enzymes were concerned. The present paper presents further evidence for this conclusion and observations on the action of various tissue extracts upon a range of acetamido compounds. It is convenient in this paper to refer to an enzyme which hydrolyses N-acetylglycine asAG deacetylase and to an enzyme which hydrolyses acetanilide as AA deacetylase. METHODS