The tryptophanase-tryptophan reaction. 9. The nature, characteristics and partial purification of the tryptophanase complex

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Abstract
The tryptophanase complex of Escherichia coli may be obtained in the cell-free condition by extraction of acetone-dried cells with half-saturated KCl solns. Tryptophanase is inhibited by Fe inhibitors, carbonyl inhibitors and BAL. Mepacrine and benzamide, which have inhibitory actions on the tryptophanase activity of viable cells, have little effect on the cell-free enzyme. Tryptophanase activity is stimulated by verdoperoxidase and cytochrome c. The enzyme complex has been resolved and shown to require pyridoxal phosphate, riboflavin and diphosphopyridine nucleotide as coenzyme factors. A partial purification of the tryptophanase complex has been achieved by ammonium sulfate fractionation. The purified fraction effects the fission to indole, pyruvic acid and ammonia with pyridoxal phosphate as sole coenzyme under anaerobic conditions. The resolved enzyme does not obtain a riboflavin prosthetic group or diphosphopyridine nucleotide and these coenzymes, therefore, appear to be concerned with the further oxidation of pyruvic acid. The fractionation removes the enzyme or enzymes effecting oxidation of pyruvic acid.