Further studies on the biotin coenzyme.

During the past several years much progress has been made in the understanding of the enzymatic functions of biotin. Although the mode of action of biotin remains to be elucidated, it is quite clear that this vitamin is involved in the oxalacetate decarboxylase system (Lardy et al., 1947; Lichstein and Umbreit, 1947; Shive and Rogers, 1947; Ochoa et al., 1947; Wessman and Werkman, 1950), the reversible deamination of aspartic acid (Lichstein and Christman, 1948; Wright et al., 1949), and the deamination of serine and threonine (Lichstein and Christman, 1948, 1949). More recently its function in the decarboxylation of succinic acid has been demonstrated (Delwiche, 1950). The coenzyme of aspartic acid, serine, and threonine deaminases has been concentrated from yeast extract (Lichstein and Christman, 1949) and liver extract (Christman and Lichstein, 1950) by means of paper partition chromatography, and by acid hydrolysis studies it has been shown to contain an acidstable material that replaces biotin for the growth of Saccharomyces cerevisiae (139). It is probable that this acid-stable component is a derivative of biotin that may be an intermediate in the synthesis of the coenzyme from biotin (Christman and Lichstein, 1950). The present communication demonstrates that this coenzyme is active also in the oxalacetate decarboxylase and succinic acid decarboxylase systems, and thus provides convincing evidence that this material is the biotin coenzyme present in nature.