Tryptophanase family (Tnase). This family belongs to pyridoxal phosphate (PLP)-dependent aspartate aminotransferase superfamily (fold I). The major groups in this CD correspond to tryptophanase (Tnase) and tyrosine phenol-lyase (TPL). Tnase and TPL are active as tetramers and catalyze beta-elimination reactions. Tnase catalyzes degradation of L-tryptophan to yield indole, pyruvate and ammonia and TPL catalyzes degradation of L-tyrosine to yield phenol, pyruvate and ammonia.