-!- The enzyme cleaves a carbon-carbon bond, releasing indole and an unstable enamine product that tautomerizes to an imine form, which undergoes a hydrolytic deamination to form pyruvate and ammonia. -!- The latter reaction, which can occur spontaneously, can also be catalyzed by EC 3.5.99.10. -!- Also catalyzes 2,3-elimination and beta-replacement reactions of some indole-substituted tryptophan analogs of L-cysteine, L-serine and other 3-substituted amino acids.