Tryptophanase, conserved site <p>Tryptophanase (tryptophan indole-lyase, TNase) (<db_xref db="EC" dbkey="4.1.99.1"/>) and tyrosine phenol-lyase (TPL) (<db_xref db="EC" dbkey="4.1.99.2"/>) are related pyridoxal-phosphate dependent homotetrameric enzymes that catalyse the reversible hydrolytic cleavage of L-tryptophan or L-tyrosine to indole or phenol, respectively, and ammonium pyruvate. These two enzymes are very similar in sequence and structure, but show strict substrate specificity. Both TNase and TPL may react by a rare S(E)2-type mechanism [<cite idref="PUB00014799"/>].</p><p> This entry represents the conserved site associated to the central region of the sequence, the pyridoxal-phosphate group is attached to the lysine residue in the central section of the sequence.</p>