The Conversion of N‐Formyl‐l‐Aspartate into Nicotinic Acid by Extracts of Clostridium butylicum

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Abstract
The rate of synthesis of nicotinic acid by partially purified cell extracts of Clostridium butylicum was increased when the substrates l‐aspartate and formate were replaced by N‐formyl‐l‐aspartate. Aminopterin (0.2 mM) inhibited the synthesis from l‐aspartate and formate, but not from N‐formyl‐l‐aspartate. N‐Formyl‐d‐aspartate did not support the synthesis of nicotinic acid. In the presence of aminopterin, radioactivity from 14C‐labelled N‐formyl‐aspartate was incorporated into nicotinic acid by partially purified cell extracts with only low dilution of the molar specific radioactivity.The pattern of labeling in the synthesised nicotinic acid showed that C‐2, 3, 7, and 6 of the nicotinic acid were derived from C‐2, 3, 4 and the formyl carbon of N‐formyl‐aspartic acid. Partially purified extracts of Cl. butylicum synthesised N‐formyl‐aspartic acid from aspartate and formate and this formylation was inhibited by 0.2 mM aminopterin.