The oxidation of nicotinic acid by Pseudomonas fluorescens

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Abstract
Cell suspensions of P. fluorescens oxidized nicotinic acid, consuming 3.9 molecules of O2/molecule of nicotinic acid attacked. The R. Q. was low at the start of the oxidation but rose to 0.90 towards the end. Degradation of the nicotinic acid did not take place under anaerobic conditions, hence the enzyme involved in the initial attack is a true oxidase. The 1st step in the degradation of the nicotinic acid molecule is apparently the opening of the pyridine ring. The specificity of the enzyme was studied. If the carboxyl group of the nicotinic acid molecule was treated to form the amide, replaced by a sulfonic acid group, an amino group, or a sulfanilamide group, or removed entirely, the enzyme failed to act on the compound. Indolylpropionic acid and L-tryptophan were not attacked. Aromatic diketones and cysteine inhibited the nicotinic acid oxidation. The effect of one could be neutralized by the other at specific concn. ratios. The enzyme studied contains a non-dialyzable metal. Attempts to obtain active cell-free enzyme prepns. were unsuccessful.

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